Method
Bake the Cakes
Preheat oven to 350°F (175°C). Grease and line two 8-inch or 9-inch cake pans.
Mix dry ingredients (flour, granulated sugar, cocoa, baking powder, baking soda, salt) in one bowl.
Mix wet ingredients (eggs, oil, buttermilk, vanilla) in another bowl.
Combine wet and dry. Stir in hot water until smooth.
Divide batter into pans. Bake for 30–35 minutes or until a toothpick comes out clean.
Cool cakes completely on a rack.
Make the Filling
In a saucepan, cook blackberries and 1/4 cup sugar until they are juicy and soft.
Add the cornstarch slurry and lemon juice. Stir until the mix thickens.
Let the filling cool fully before using.
Whip the Cream
Beat heavy cream, powdered sugar, and vanilla until stiff peaks form.
Assemble the Cake
Place one cake layer on a plate. Spread the cooled blackberry filling evenly on top.
Add the second cake layer.
Spread whipped cream over the top and sides.
Decorate and Chill
Add fresh blackberries, edible flowers, and dark chocolate shavings. Dust lightly with cocoa powder.
Chill the cake for at least 1 hour before slicing for best results.
Notes
Use room temperature eggs for better batter texture. Let cakes cool fully before you add the filling to avoid melting the cream.