3½ cups (438 grams) all-purpose flour1 tablespoon (15 grams) baking powder1 teaspoon (3 grams) kosher salt1¾ cups (350 grams) granulated sugar1 cup (224 grams) neutral oil3 large eggs (150 grams), room temperature1 tablespoon (13 grams) vanilla extract1½ cups (360 grams) sour cream, room temperatureVanilla Simple Syrup (recipe follows)Mascarpone Whipped Cream (recipe follows)3 to 3½ cups (about 520 grams) assorted fresh berries, sliced and chopped as needed (see Note)
Preheat oven to 350°F (180°C). Spray 2 (8-inch) round cake pans with baking spray with flour. Line bottom of pans with parchment paper.
In a large bowl, whisk together flour, baking powder, and salt. In another large bowl, whisk together sugar, oil, eggs, and vanilla until smooth; whisk in sour cream.
Gradually add flour mixture to sugar mixture, whisking just until no dry streaks remain. Divide batter between prepared pans (about 2¾ cups or 765 grams each), spreading smooth.
Bake until top is golden and a wooden pick inserted in center comes out clean, 35 to 40 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks.
Level cooled cake layers, if desired. Place 1 cake layer on a serving plate. Using a pastry brush, brush half of Vanilla Simple Syrup onto cake layer. Spread2 cups (300 grams) Mascarpone Whipped Cream onto cake layer. Top with about two-thirds (about 300 grams) berries, sliced and chopped as needed, pressing berries into filling. Top with remaining cake layer, and brush remaining vanilla syrup onto layer. Spread remaining Mascarpone Whipped Cream on top and sides of cake. Refrigerate cake for at least 30 minutes before serving. Top with remaining berries just before serving. Refrigerate in an airtight container for up to 3 days.
Note: We used strawberries, raspberries, blueberries, and blackberries, but you can use any combination of berries or any single berry you like. Halve, slice, or chop large berries as needed before assembling layers in step 5.