1 cup sugar, plus extra for sprinkling
Grated zest of 1 lemon
2 large eggs
1/4 teaspoon salt
1 teaspoon pure vanilla extract
1/2 teaspoon pure almond extract
1 cup all-purpose flour
1 stick (8 tablespoons) unsalted butter, melted and cooled
About 1/4 cup sliced almonds (blanched or not)
Center a rack in the oven and preheat the oven to 350 degrees F. Butter a seasoned 9-inch cast-iron skillet or other heavy ovenproof skillet, a 9-inch cake pan or even a pie pan.
Pour the sugar into a medium bowl. Add the zest and blend the zest and sugar together with your fingertips until the sugar is moist and aromatic. Whisk in the eggs one at a time until well blended. Whisk in the salt and the extracts. Switch to a rubber spatula and stir in the flour. Finally, fold in the melted butter.
Scrape the batter into the pan and smooth the top with a rubber spatula. Scatter the sliced almonds over the top and sprinkle with a little sugar. If you’re using a cake or pie pan, place the pan on a baking sheet.
Bake the cake for 25 to 30 minutes, or until it is golden and a little crisp on the outside; the inside will remain moist. Remove the pan from the oven and let the cake cool for 5 minutes, then run a thin knife around the sides and bottom of the cake to loosen it. You can serve the cake warm or cooled, directly from the skillet or turned out onto a serving plate.