1 3/4 cups cake flour (we spoon flour into the dry measuring cup & level off)
1 cup granulated sugar
1/4 cup dutch process cocoa powder
3/4 tsp baking soda
1/2 tsp fine salt
1/2 cup buttermilk
1/2 cup vegetable oil
1/2 cup sour cream
1 tsp red food coloring (plus a drop for the filling)
2 tsp cider vinegar
1 tsp pure vanilla extract
1 large egg (at room temperature)
one 85 g semisweet chocolate bar
1 tsp coconut oil
1 cup raspberry jam
cream cheese frosting:
one 226 g package cream cheese (at room temperature)
6 tbsp unsalted butter (cubed, at room temperature)
1 cup confectioners' sugar
1/2 tsp pure vanilla extract
a pastry bag fitted with a large round tip
a plastic straw