In a saucepan over medium heat, stir together 1 1/2 cups raspberries, sugar and water until the sugar is dissolved. Heat the mixture to boiling, stirring often. Reduce heat and add the vanilla.
In a small cup, combine the cornstarch and two tablespoons of water. Mix well.
Pour this into the boiling raspberry mixture. Stir and boil over medium-low heat for 4 minutes or until the mixture has thickened a bit.
Remove the pan from the heat.
Add 1 tablespoon of butter and mix until the butter has completely melted.
Allow the mixture to cool for 15 minutes, then add the last of the raspberries and stir to mix. Refrigerate the filling until you assemble the cake.
Make the Cake:
Preheat oven to 350 degrees. Grease and flour 2 round 8-inch cake pans.
Place the flour, sugar, cocoa, baking powder, baking soda and salt in a bowl and whisk together.
In a stand mixer, mix the buttermilk, oil, eggs, vanilla together. Slowly add in the mix of dry ingredients while the mixer is on low. Add the coffee and make sure everything is combined. The batter will be very thin.
Pour the batter into the prepared pans and bake for about 30 minutes or until a toothpick inserted in the middle comes out clean.
Allow the cakes to cool on a wire rack for 10 minutes. Turn the cakes out onto a cooling rack.
Once the cakes are cooled, slice each cake layer in half so you end up with 4 layers.
Crumble one layer into cake crumbs. These crumbs will be used to decorate the cake.
Make the Whipped Cream Frosting:
Chill the metal bowl of a stand mixer (or a large metal bowl to use with a hand mixer) for at least 5 minutes.
Add the heavy cream and powdered sugar to the bowl. Beat on high for 3-5 minutes or until stiff peaks form.
Place the frosting in the refrigerator until you are ready to assemble the cake.
To Assemble the Cake:
Place one cake layer down on a cake plate.
Top with 1 cup of whipped topping. Spread to cover the cake.
Spread 3/4 cup cooled raspberry filling over the whipped cream.
Place a 2 layer of cake on top of the filling.
Repeat with another cup of whipped cream, 3/4 cup of raspberry topping and third cake layer.
Frost the entire outside of the cake with the whipped frosting, setting aside about 1 1/2 cups for making dollops of frostings around the top.
Press the crumbled cake crumbs onto the bottom half of the cake all around the sides.
Spoon the remaining raspberry filling on top of the cake to about 1" from the edge.
Place the reserved whipped frosting into a large decorating bag with a Wilton 1M tip. Squeeze stars around the outer top edge of the cake.
Sprinkle the cake with shaved milk chocolate if desired.
Refrigerate immediately until serving. Store any leftovers in the refrigerator in a covered cake container.
The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**