The annual birthday cake post | French yogurt cake with lemon curd buttercream icing

If you've ever seen French yogurt cake served like this, I'd like to hear about it!

The recipe
Cake ingredients
Canola or vegetable oil, 1 cup (I usually substitute olive oil but not when making this as a birthday cake)
Greek yogurt (full fat) 1.5 cups
Lemon zest, about 3 lemons or 3 tbsp
Cake flour (unbleached), 3 cups plus 6 tbsp
Baking powder, 4 tsp
Kosher salt, 1.5 tsp
Sugar, 2 cups
Large eggs, 4
Vanilla extract, 1 tsp

Gel food coloring (optional)

Icing

Powdered sugar, 1 1/3 lb
Lemon curd, 10 oz
Juice of 1 lemon

Vanilla extract, 1 tsp

Butter, 1 cup

Salt, 1/4 tsp

Berry sauce (optional)
Mixed berries, 1 cup (raspberries, blackberries, strawberries and/or blueberries, fresh or frozen)
Juice and zest of 1 lemon
Pomegranate juice, 1/3 cup

Equipment
3 9" cake pans
Checkerboard cake ring (optional; from Nordic Ware or Wilton)

Directions
1. Preheat oven(s) to 350˚F.
2. Line pan(s) with circles of parchment and grease with butter and dust with flour.
3. Whisk flour, baking powder, and kosher salt in a bowl.
4. Using your fingers, rub sugar with lemon zest in a large bowl until sugar is moist and aromatic oils released. 

5. Add yogurt, oil, eggs, and vanilla extract; whisk to blend. 

6. Fold in dry ingredients just to blend. 

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To make checkerboard pattern
7. Divide batter in half or in thirds; for six colors, divide each third in half again. I recommend using a measuring cup or identical bowls to divide as accurately as possible. 

8. Dye each bowl the desired hue and shade using gel food coloring.

9. Place checkerboard cake ring into the first pan. Spoon batter in the desired color into the appropriate ring. (Don't forget that the rings use different quantities of batter when apportioning!)

10. Remove the ring, rinse and repeat with the next two pans. 

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11. Bake until top of cake is golden brown and a tester inserted into center comes out clean, about 15-18 minutes per layer.

12. Let cake cool in pan on a wire rack for 15 minutes. Invert onto rack; let cool completely.

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To make icing

13. Whip powdered sugar, lemon curd, lemon juice, salt and vanilla until smooth.

14. Beat in butter, about 10 minutes. 

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To make berry sauce

15. Bring berries, lemon zest, and juices to a boil and reduce to simmer.

16. Stir and mash to break up berries into small pieces.

17. Simmer about 10 minutes until beginning to thicken.

18. Chill in refrigerator to bring to room temperature or cooler before serving. 

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19. Assemble cake with icing beginning layer and on top as desired. 

20. Decorate and serve, with berry sauce on the side.

The story

The first time I made this simple classic cake, about four years ago, it served two functions: (1) to celebrate the end of a rotation (for my residents) and (2) to provide a vehicle for the peach-nectarine-cherry buttercream icing I made out of the blue one day. 

It was really delicious.

Many better food blogs than this have described the backstory of French yogurt cake. This one is my favorite so far: http://thecafesucrefarine.com/2015/04/french-grandmothers-lemon-yogurt-cake/. I had heard none of those until two days ago, when I started looking for recipe variations that might be more lemony than the one I knew whilst standing in an aisle at Party City with a dazed look on my face.

It started a month or two ago, when my son stumbled across a YouTube video called "How to Make a Candyland Cake". I was immediately horrified at the idea of feeding him boxed sheet cake topped with Starburst, circus peanuts, and Technicolored Twizzlers. But it did look fun. (He followed up this click by clicking on a video of a cute English girl making a Snakes and Ladders cake with her mom, adorned with chocolate ladders and gummy worms. F. asked for the next month how he could slide down a snake.)

I then asked him what kind of cake he wanted, and he immediately replied, "Blueberry!" I sighed and asked again a week or two later. By then, he had moved on to lemon cake, which he wanted to be baked into a rainbow or five or six layers. I contemplated this option for a bit - last year's birthday cake was lemon raspberry, with lemon curd baked into the cake batter and lemon curd and raspberry jam spread between the layers. It was a bit sweeter and stickier than I would have liked, so I didn't want to repeat it. I contemplated making him a strawberry cake instead, but he's a February baby, and reliably delicious strawberries are hard to come by in February and definitely not local. Also, I had been planning to make (or, oh okay fine, have shipped) a Milkbar strawberry lemon cake for my mom's birthday in March. 

So I tried to talk him into a Southern caramel cake, which I have been dying for since we had one from Lady of Cakes for my grandmother's 90th birthday in 2010. (It was decorated with cherry blossoms!) I tried. He almost agreed. The problem was, every time someone asked him unprompted, when I wasn't around, he went back to saying that he wanted a lemon cake.

Which brought me to the point, the day before his birthday party, where I was wandering around Party City in search of decorations for the Candyland theme, and still undecided about exactly what kind of cake to make. I Googled "lemon layer cake" and, unexpectedly, "French yogurt cake" popped up. I'd forgotten about the lemon zest. Concerned that it might not be sufficiently lemony, I started searching for ways to add lemon juice to a recipe with relatively little liquid, and in the process, I came up with the idea of adding lemon curd to buttercream icing in order to give the cake more lemon flavor. (In Party City, I also discovered the checkerboard cake ring, a brilliant invention.)

The cake came beautifully (it always does) but I was concerned that the frosting was too sweet, so I threw together a berry sauce at the last minute. Great combination, but it also turned out that the balance of sweetness in the iced cake was perfect (most, but not of all, of the adults, avoided eating the decorations).

The best part was the look of pure, unbridled joy on F.'s face. Birthday cake of a four-year-old's dreams!