• Preheat oven to 350°F
• Grease 3 8-inch round cake pans with butter, line with parchment paper, butter again.
• In a large bowl, beat together the coconut oil, sour cream, eggs, sugar, buttermilk, and vanilla.
  1 cup melted coconut oil, ½ cup sour cream, 3 large eggs, 1 cup granulated sugar, 1½ cups buttermilk, 1 tbsp vanilla extract
• Add the flour, baking powder, baking soda, and salt. Mix until just combined.
  3¾ cups cake flour, 2 tsp baking powder, 1 tsp baking soda, 1 tsp kosher salt
• Fold in the blackberries and swirl in 3/4 cup blackberry jam, leaving a few streaks of jam throughout the batter, it shouldn't be fully incorporated.
  1½ cups fresh or frozen blackberries, 3/4 cup blackberry jam
• Divide the batter among the 3 cake pans and bake for 30-35 minutes, until the tops are just set and no longer wiggly in the center. Remove and let cool for five minutes. Run a knife around the edges of the pan and turn the cakes out onto a cooling rack. Cover and let the cakes cool completely before assembling.

Frosting

• In a bowl, beat together the butter and powdered sugar until light and fluffy.
  3 sticks salted butter, 1½ cups powdered sugar
• Add the melted white chocolate and vanilla and beat until combined.
  8 ounces white chocolate, 2 tsp vanilla extract
• To assemble, place one cake layer on a serving plate. Spread 1/3 of the frosting over the cake and layer with about 1/4 cup of jam. Repeat with the remaining cake layers. Be careful not to overfill your layers or the cake will be hard to slice. Lightly frost the outside of the cake, then decorate with smashed raspberries. Chill 30 minutes. Serve or store in the fridge for up to 3 days.