Preheat the oven to 350 degrees. Spray a 9-inch round cake pan with cooking spray, line the bottom of the pan with parchment, then spray the parchment. Set the pan aside.
Use a rubber spatula to stir the sugar and butter together in a large bowl. Mix in the eggs, almond extract, and lemon zest (if using) to combine.
Sift the flour and salt into the bowl, then mix until just incorporated. Spread into the prepared cake pan and smooth the top.
Sprinkle the sugar over the cake, then top with the almonds.
Bake 34 to 44 minutes, until the top is light golden brown and a cake tester inserted into the center of the cake comes out clean.
Cool the cake on a wire rack, dust with powdered sugar, then serve.
Uneaten cake can be stored at room temperature, covered, for up to 2 days or in the freezer, tightly wrapped, for up to 2 months.
