I'm a big fan of True Blood on HBO. For the season finale I made a red velvet cake with strawberry and raspberry filling, and did a little creative cake frosting (I've been getting into cake decorating this year) The results looked great and were delicious!
I just used basic red velvet cake mix and vanilla frosting but for the filling I adapted a recipe from BakeSpace
Berry Fruit Filling
1 pint of raspberries
2 cups of strawberries,
1/4 c sugar
1/2 c water
2 T corn syrup (add more as necessary to thicken to a gel like consistency)
1 t vanilla extract
Coarsely chop fruit. Puree 1/2 a cup.
Take pureed berries and cook with water in a saucepan over medium heat for 2 minutes. Mix Sugar and Cornstarch. Gradually stir into pureed berry juice. Continue to cook while stirring constantly until thickened. Add in chopped berries and cool to room temperature before filling cake.
When filling a cake I always crumb frost the layers so that the filling won't soak into the cake. With this cake it soaked in a little so next time I won't thin the frosting as much, but it still tasted great.
This filling could be made with any different combination of berries. I always seem to like mixing flavors rather than having just one single one but that would work too! As you can see the cake filling is bleeding a little bit this was on purpose since it was for True Blood and I wanted a vampire themed cake, but this can be avoided by building up a frosting border around the cake and being sure not to pour the filling too close to the edges because when you put the top layer of the cake on it will squish out.
Note- cakes with fruit filling should be refrigerated, but it tastes best freshly baked anyways so eat up!