Preheat oven to 350 degrees. Wash and dry three 28 ounce tin cans and remove the labels. Line each with parchment paper cut to fit on the sides and bottom. Spray with non-stick spray and set aside.
In a large mixing bowl, combine butter, sugar, salt, vanilla, and baking powder. Beat together until light and fluffy.
Add flour and beat until batter resembles a thick paste.
Add eggs one at a time, scraping down bowl until very light and fluffy.
Transfer cake batter evenly into three different bowls, then add food coloring to each batter to desired color.
Alternate spooning colored batter into each can until each can has the same amount of batter.
Swirl batter in each can with a knife, making concentric circles as you pull the knife upward.
Place cans on a baking pan and transfer to pre-heated oven. Bake for 35-40 minutes or until a skewer inserted into the center comes out clean. Transfer cans to a cooling rack and let cool completely.
Meanwhile, for filling, combine all ingredients in a medium bowl and blend with a hand mixer until smooth. Add food coloring to desired shade of purple and set aside.
For ganache, add white chocolate to a small glass bowl and pour hot cream over chips. Stir quickly with a spoon until chips are completely melted. If chips are not completely melted, you can microwave them for 5 or 10 seconds, then stir again. Add food coloring to desired shade of purple. Set aside.
Remove cakes from cans and remove parchment. Cut each cake crosswise into three sections.
Place bottom section of each cake on a flat surface. Spoon about 1/4 cup of mascarpone creme onto each bottom section. Top with berries, then repeat with the next layer of cake, creme, and berries. Add top layer of cake, then spoon warm ganache over the top. Place more berries on top and dust with powdered sugar. Serve.
You can save time by eliminating the food coloring and using a bundt pan instead of the cans.