Lemon Butter Cake
This recipe is adapted from The Simple Art of Perfect Baking by Flo Braker (Houghton Mifflin 1992).
3 cups cake flour
3 teaspoons baking powder
1/4 teaspoon salt
8 ounces (2 sticks) unsalted butter, softened
1 1/2 cups sugar
4 eggs, lightly beaten
1 cup whole milk
1/2 cup lemon juice (about 2 lemons)
Zest of 1 lemon
Start with all ingredients measured out and at room temperature.
Preheat oven to 325 degrees. Butter a 9-by-13-2-inch baking pan.
Sift cake flour, baking powder and salt into a bowl. Set aside.
In an electric mixer, beat butter and sugar until fluffy, scraping down sides of the bowl periodically.
Add beaten eggs slowly and continue beating until thick and double in volume.
Remove bowl from mixer and carefully fold in one-quarter of the flour mixture with a spatula. Then fold in one-third of the milk. Repeat the folding of the flour and milk alternately, ending with the flour. Last, mix in the lemon juice and zest.
Bake in center of oven until top is set and springs back to the touch. Check after 30 minutes.
Remove from oven and let rest about 15 minutes.
While the cake bakes, make frosting and filling:
Lemon or Lime Curd Filling
To make the curd the color of lime gelatin and create the right contrast for the striped cake effect, you will have to add a drop or two of green food coloring. But the flavor of real fruit — as opposed to Jell-O — is worth the effort.
2/3 cup good-quality lemon or lime curd (available at many supermarkets in the jam and jelly aisle)
A few drops green food coloring (optional)
Mix curd and food coloring, if using. Thin slightly with a few drops of warm water until the curd runs in a not-quite-steady stream from a spoon. It should be the consistency of a very soft pudding or unset gelatin. If it's too runny, it won't stay in the holes, so add a tablespoon more of curd from the jar and stir like crazy. If it's too thick, it won't go down the holes and you should add a bit more water.
Lemon Mascarpone Topping
More sophisticated and tangy than whipped topping, but unfussy at the same time, mascarpone, right out of the tub, is the right texture for spreading on almost anything.
16 ounces mascarpone, at room temperature (available in the supermarket dairy case)
1/2 cup confectioner's sugar (or more to taste)
2 teaspoons almond extract
Zest of 1 to 2 lemons (about 1 tablespoon)
4 tablespoons lemon juice
Stir all ingredients in a small bowl and set aside.
After the cake has cooled for about 15 minutes, poke holes in it with a straw at about 1-inch intervals, removing any cake clinging to the inside of the straw. If the straw begins to bend, snip off the bottom and keep going.
Carefully spoon the filling into the holes with an ordinary teaspoon. If it comes out of the holes, don't worry. The topping will cover it up. You may need to go over the holes twice if they don't fill up the first time.
Spread the mascarpone topping thickly over the cake while still warm, cover loosely with plastic wrap and put the whole thing in the refrigerator for at least two hours or until cold.
Serve slightly chilled or at room temperature, decorating each piece with candied lemon peels, if you like.
Store in refrigerator wrapped tightly for up to 2 weeks. I don't recommend freezing it after frosting because the mascarpone loses its texture in the thawing process.