- Grated zest and juice of 2 lemons
- 3/4 cup plus 2 tablespoons sugar
- 4 extra-large eggs
- 6 tablespoons unsalted butter, cubed
- 9 tablespoons unsalted butter, softened
- 1 cup plus 1 tablespoon flour
- 1 cup plus 1 to 2 tablespoons sugar
- 1 teaspoon baking powder
- 1/2 teaspoon kosher salt
- 2 extra-large eggs
- 1/2 cup ground toasted almonds
- 2 tablespoons toasted sliced almonds
- 1 tablespoon almond liqueur (optional)
- 1/2 cup heavy cream (optional)
- 2 tablespoons confectioners' sugar or as needed
Combine the lemon zest and juice in a nonreactive saucepan with the sugar and eggs and beat well. Add the butter and cook over medium heat, stirring constantly with a rubber spatula or wooden spoon, until the sugar dissolves and the mixture thickens into curd. Be sure to keep scraping the bottom of the pan during the few minutes this takes you; you don't want the eggs to scramble before the curd forms. If you're the nervous type, make the curd in a heatproof bowl over a pot of boiling water (the bowl shouldn't touch the water). The curd will take just a little longer to thicken, about 5 minutes. Strain the crud into a bowl and press a piece of plastic wrap against the surface so a skin doesn't form. Refrigerate until cool, at least 1 1/2 hours.
Cream the remaining 8 tablespoons butter in a large bowl with 1 cup of the sugar until light and fluffy. Sift the remaining 1 cup flour, the baking powder, and salt together and stir into the creamed butter.
Scrape the batter into the prepared pan. Drop 8 individual tablespoons of lemon curd evenly around the outside of the cake, leaving a 1-inch border around the edge. Try to place the curd so there's an even amount of cake batter between each dollop of curd. Drop 3 tablespoons curd in the center. Refrigerate any remaining curd for another use (hint: breakfast toast). Sprinkle the top of the cake with sliced almonds and 1 to 2 tablespoons sugar, according to taste.
Bake until the cake is toasty brown on top and a toothpick or knife inserted into the cake comes out clean (be sure not to insert it near the curd), about 40 minutes. Let cool for 10 minutes, then remove the sides of the pan and let cool completely on a rack.
If serving the cake with whipped cream, add the almond liqueur to the heavy cream and beat until the cream is stiff. Sift a thin, even layer of confectioners' sugar over the top of the cake. Present the cake at the table and offer the almond whipped cream on the side.