Italian Plum and Almond Cake

Preheat oven to 350°. Generously coat a 10" cake or springform pan with nonstick spray.

Whisk flour, almond meal, baking powder, and salt in a medium bowl. Using an electric mixer on medium speed, beat butter, granulated sugar, and brown sugar in a large bowl until pale and creamy, about 4 minutes. Add eggs one at a time, mixing well to incorporate after each addition, then add orange zest and vanilla paste and beat until fully incorporated, about 3 minutes. Reduce speed to low and gradually add dry ingredients; beat just until smooth and no lumps remain, about 30 seconds.

Scrape batter into prepared pan and arrange plums, cut side down, on top of batter, taking care not to push the plums into the batter (the batter will rise as it bakes, slightly submerging them). Sprinkle demarara sugar over and bake cake until top is golden brown, plums are very soft, and a tester inserted into the center comes out clean, 50–60 minutes. Transfer to a wire rack and let cake cool in pan at least 30 minutes. Run a sharp knife around sides of pan to loosen cake. Carefully invert cake onto a rimmed baking sheet, then invert again onto a platter or cake stand. Dust with powdered sugar just before serving.

Do Ahead: Cake can be made 8 hours ahead. Cover tightly and let stand at room temperature.