Preheat oven to 350F. Combine the cake mix, champagne, eggs and oil and whisk until smooth.
Pour the cake mix into two greased circular cake pans and bake at 350F until a toothpick comes out clean (about 25-30 minutes).
Place each cake in the refrigerator until completely cooled (about 30-45 minutes).
For the frosting, Use a mixer (use the paddle attachment if you own one) to cream the butter until light and fluffy (about 3 minutes).
Slowly add the sugar, scraping down the sides of the bowl, a little at a time.
After all of the sugar is added, add the vanilla and continue beating until the icing is smooth and light (icing may appear dry).
Chop half of the raspberries in a food processor (about 2 minutes). Set aside the remaining fruit for toppings.
Next, add the milk and processed raspberries to the frosting and continue to mix until smooth (about 2 minutes).
Remove the cakes from the fridge, frost the top of one, then stack the two cakes to finish frosting.
Top with fresh raspberries before serving.