Apricots and almonds are a natural pairing, and we've capitalized on that marriage in this rich almond cake. Excellent plain, this cake is even more memorable topped with fresh apricots. Serve warm with whipped cream or crème Anglaise sauce.
Position a rack in the middle of the oven and preheat to 350 degrees F. Butter the sides and bottom of a 9-inch round cake pan and set aside.
Place the butter and almond paste in the bowl of an electric mixer and beat until the mixture is creamy, 2 to 3 minutes. Add the confectioner's sugar and beat until the mixture is combined. Add the eggs, one at a time, beating until each is well-blended, stopping to scrape down the sides of the bowl as needed.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry mixture to the batter, alternating with the sour cream. Beat just until blended.
Pour the batter into the prepared pan. Arrange the apricot slices on top of the cake in a decorative pattern, pressing them gently into the batter. Bake for 30 minutes. Lightly brush the apricots with the melted butter and sprinkle with the turbinado sugar. Continue baking until the cake is set and a skewer or toothpick inserted into the center comes out clean, an additional 15 to 20 minutes.
Serve warm, or cool to room temperature and wrap tightly in plastic wrap. The cake can be refrigerated for up to 2 days. Allow to return to room temperature before serving.