Tarte au Citron, AKA the Lemon Tart

The lemon tart. One of my favorite desserts. 

Really, I love a lot of lemon desserts. Lemon tarts. Lemon bars. Lemon cake. Give me something lemon-y and sweet and I'm probably going to love it. 

The lemon tart, frequently referred to as a tarte au citron on GBBO, is really not a very difficult dessert in my opinion. This isn't the first time I've made a lemon tart - this is just the first time I've made this particular crust with this particular variant on the filling. 

Lemon tarts are technically a custard tart, so this particular bake fits in a lot of different challenges over the seasons. 

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I decided to include it on my blog as the Signature Bake from series 5 (Netflix collection 1) episode 5 and the Technical Bake from the same season, episode 10. The tart au citron featured as part of a 3 part technical bake, but it also featured in episode 5 when Norman made his "plain" tarte au citron.

It could be considered a tart for many different episodes on many different seasons of GBBO, but I'm going to stick to these two episodes so that I challenge myself to get out of my comfort zone a little more with future bakes.

Lemon tart is, as I mentioned, a dessert I consider pretty easy to make. I have several recipes I've used over the years to make them, but this time I decided to use Mary Berry's recipe to see what might be different about it. 

Ingredients
For the pastry

• 175g/6oz plain flour
  • plain flour = all purpose
  • 175 g of flour is about 1.5 cups, plus two tablespoons.
• 100g/3½oz cold butter, cut into small cubes
  • And trust me. You want the butter cold. 
  • this is approximately a smidge less than 1.5 stick of butter. Yes. A smidge. It's a technical term.
• 25g/1oz icing sugar
  • icing sugar = powdered sugar
• 1 free-range egg yolk
• 1 tbsp cold water

For the filling

• 5 free-range eggs
• 125ml/4fl oz double cream
  • double cream = heavy whipping cream
• 225g/8oz caster sugar
  • This is a little under 2 cups of sugar.
• 4 lemons, juice and zest
• icing sugar, for dusting

Equipment

• food processor (optional)
• tart pan (or pie pan)
• rolling pin
• bowl
• whisk
• rimmed baking sheet

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Method
1) To make the pastry, place the flour, butter and icing sugar into a food processor. Pulse briefly until the mixture resembles breadcrumbs, then add the egg yolk and water.

• You can also do this by hand if you don't have a food processor. I normally work by hand, but this was so quick and easy that I think I'm a convert to the food processor life!
• If you want to do this by hand, you will rub the butter into the flour, flattening the pieces of butter out and then letting the mixture get crumbly. 
• You'll keep working the pastry mix until the dough just comes together.

2) Pulse again until the mixture sticks together in clumps then tip onto a work surface and gather it into a ball with your hands. Knead the pastry just two or three times to make it smooth. If your butter was a bit too soft, the pastry might be too. If so, wrap it in parchment paper and chill for 15 minutes.

• Soft butter in any form of pastry is no joke. If your butter has gotten warm, pop your pastry dough into the fridge. 
• Honestly, I feel like it's just good practice to go ahead and pop it in the fridge for a few minutes regardless. 

3) Grease a 23cm/9in loose-bottomed, fluted tart tin.

• If you don't have a tart tin, you can use a pie tin/plate. I don't think anyone will fault you for doing so. I certainly won't ;)

4) Lay a piece of parchment paper on the work surface. Remove the base from the tart tin and lay it on the paper. Using a pencil, draw a circle onto the paper 4cm/1½in bigger than the tin base.

5) Dust the base of the tin with flour. Place the pastry ball in the centre of the tin base and flatten it out slightly. Roll out the pastry, still on the base, until it meets the circle mark. As you are rolling out, turn the pastry by turning the paper. Gently fold the pastry surrounding the tin base in towards the centre.

6) Carefully lift the tin base off the work surface, drop it into the tin, then ease the pastry into the corners and up the sides of the tin, pressing the overhang lightly over the rim. If the pastry has cracked at all, simply press it together to seal. Press the pastry into the flutes of the tin then lightly prick the base with a fork, but not quite all the way through. Place the pastry-lined tin on a baking tray, cover loosely with cling film and chill in the fridge for 30 minutes. Preheat the oven to 200C/400F.

• If your oven heats in increments of 5, I'd say putting the oven at 390 or 395 is closer to 200C, but that's just me being a little anal retentive about it. It will be fine at 400F. 

7) Remove the cling film from the pastry case and line with foil so it supports the sides, then fill with baking beans. Bake blind for 12-15 minutes, until the pastry is set, then lift out the foil and beans. Carefully trim the excess pastry from the sides using a sharp knife, holding the knife at a sharp angle and slicing away from you. Remove the trimmings from the sheet. Return the empty pastry case to the oven for another 10-12 minutes or until it is pale golden and completely dry. Set aside to cool while you make the filling. Reduce the oven temperature to 170C/325F. 

As a note here - the recipe on the BBC site says 325. I didn't double check that number and set that to my temperature to bake the filling. After the fact, and looking up the conversion now, I would actually say that 170C is closer to 350F than it is to 325F. If your oven heats in increments of 5, I'd actually recommend setting your oven temp to 340F.

A lower temperature is probably a safer option if you've never made a custard tart of any form before, but in the future I will set my oven to 340 - and I'll explain why in just a little bit. 

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​8) For the filling, break the eggs into a large bowl and whisk together with a wire whisk. Add the rest of the filling ingredients and whisk again until they are all well combined. Pour the filling mixture into a jug, then into the cooled baked pastry case. To prevent it spilling as it goes in the oven, pour in most of the filling so it almost fills the tart, carefully sit the baking sheet and tart on the oven shelf, then top up with the rest of the filling to completely fill it. Bake for about 30-35 minutes or until just set but with a slight wobble in the centre.

9) Leave to cool slightly then, when the pastry seems firm enough, remove the tart from the tin. The easiest way to do this is to place the base of the tin on an upturned can or jam jar and let the outer ring fall to the work surface. Transfer the tart to a serving plate and serve warm or cold, dusted with sifted icing sugar.

Final Thoughts
So, I managed just barely to not overcook my lemon tart. 

I've made lemon tarts before. I got cocky. But just because you've made a recipe mutliple times doesn't mean you can't or won't fuck it up. I know this. Fortunately, I did save this tart just a minute or two before it got really overbaked and the custard turned into scrambled egg. 

You can tell it's overbaked because of the cracks on the top, though. A properly baked lemon tart won't crack like that because you didn't leave it in the oven too long. 

Some of you reading may wonder how you can tell when a custard tart is ready to come out of the oven. "Slight wobble" is just vague enough to make it a very subjective measure. You're looking for a jello-like jiggle in the center of your tart. Just enough of a wobble to make you go "hmm that doesn't seem set" and then you pull it out of the oven right then to let it cool and set. The tart will seem underdone because the final phase of cooking/setting happens outside the oven. So. Look for a wobble. 

Here's the reason I overbaked my tart: when I checked it at 30 minutes, All except for a half inch ring near the crust was still liquid-y and sloshing when I gave it a gentle jiggle. I set the timer for 10 minutes - which was a huge overcorrection on my part. 5 minutes was more than enough, but I had a moment of "it's so liquidy, I should do 10". 

10 was too much. Not way too much, but too much. My tart did not have hardly any wobble. "Ah shit" was my immediate reaction as I pulled it free of the oven's confines. But it came out all right. The tart tasted delicious, the custard was still smooth aside from two small scrambled egg-like clumps I found in the middle - and it was all thumbs' up around this household.

To the point I didn't get to take any samples to friends. 

Overbaking aside, something else I want to note is this: place your tart tin or pie tin in a baking sheet when you're going to bake the filling. Use the method that Mary Berry recommends of filling the tart only partially before you put it in the oven, then fill it the rest of the way. 

I was sloppy the night I made this tart and had determined I had steady enough hands that it would be fine to fill it and then put it in the oven. 

It was not fine.

I sloshed lemon tart filling all over myself, all over the counter and the floor. Lemon filling spilled over the sides of the tart and into the tart tin, onto the baking sheet. It was everywhere. I was a sticky, lemony mess for the entire time the tart baked and I tried to clean everything up. 

​Worth it. 

As a result of all this sloshing, my crust lost some of its structural integrity when it came time to slice and serve it. Still, it tasted phenomenal, so this is really just a minor issue. 

One other thing of note: my tart tin is a little too small for this recipe. I think it's about 1 inch smaller than needed. It still came our really well, and honestly I loved getting to look at beautiful fluted edges on my tart before Andrew and I promptly demolished it. 

I feel like lemon tarts seem intimidating, but I think they're actually pretty straightforward and simple. I have, admittedly, been baking for a long time, but this is one of those recipes that never intimidated me from the beginning - so try it out if you love lemon desserts the same way I do. You won't regret it!

Serve it with a dusting of powdered sugar, or go to the trouble of making something extra for it like whipped cream or meringue. It's hard to go wrong!