Serves 8. Recipe adapted from Floating Kitchen.
Preheat oven to 350 degrees. Spray a 10-inch springform pan with non-stick spray. Line the bottom of the pan with a round of parchment paper. Spray the parchment paper as well. Set aside.
In the bowl of a stand-mixer fitted with the paddle attachment, cream 1 cup of the sugar and the butter together until light and fluffy, about 3 minutes. Turn the speed down on the mixer and add the eggs one at a time, followed by the sour cream, orange zest, vanilla, and almond extract.
In another bowl, stir together the flour, almond flour, baking powder, baking soda, and salt until combined. With the mixer on low, add the flour mixture to the wet ingredients gradually, scraping the bottom and sides of the bowl as needed, until everything is combined. The dough will be thick and sticky.
Using an offset spatula, spread half of the batter evenly into the prepared springform pan. Distribute half of the rhubarb over top of the batter in a single layer. Spread the remaining batter over the rhubarb. Distribute the remaining rhubarb on top of the cake. Sprinkle with almonds, then sprinkle everything with the remaining 1 tablespoon of sugar.
Bake until browned and set in the center, about 60-70 minutes. Allow the cake to stand on a cooling rack on the counter for at least 10 minutes before releasing from the springform pan. Dust the cake with powdered sugar, then slice and serve warm.