Preheat oven to 350 degrees F (175 degrees C). Spray the sides and bottom of a Nordic Ware Charlotte Cake Pan with Non-Stick Baking Spray (to taste).
Whisk together the Cake Flour (1 3/4 cup), Baking Powder (2 teaspoon) and Salt (1/4 teaspoon); set aside.
Using a handheld or stand mixer fitted with a paddle attachment, beat the Unsalted Butter (1/2 stick) and Granulated Sugar (1 cup) together on high speed until smooth and creamy, about 2 minutes.
Scrape down the sides of the bowl. Add the Egg (2) and Pure Vanilla Extract (1 teaspoon). Continue beating on medium-high speed until combined, then add in the Sour Cream (1/3 cup) and Whole Milk (3/4 cup).
Scrape down the sides of the bowl. Add half of the flour mixture and continue blending just until incorporated; add remaining flour mixture and again continue blending just until incorporated. Do not overmix! The batter will be slightly thicker than a normal cake batter.
Pour the batter into the prepared cake pan – filling up the pan 2/3 full. (This pan holds 6 cups of batter, but you will only use 4-1/2 cups for this recipe.) Tap the pan on a towel-covered countertop a few times and let it sit for a few minutes before baking to release any large air bubbles.
Bake for 24-28 minutes, or until the top is golden and bounces back when touched lightly in the center and a toothpick inserted in the center comes out clean.
Remove from oven and allow to cool in pan for 10 minutes.
Give the pan a gentle shake sideways, and then place a serving platter on top and invert the cake, gently patting the top of the pan until the cake releases. Perfect every time! Cover cake and let it cool completely before filling.
In a chilled medium stainless steel bowl, beat the Mascarpone Cheese (8 ounce), Heavy Cream (1 1/2 cup) and Vanilla Bean Paste (2 teaspoon) until combined.
Gradually add the Granulated Sugar (1/4 cup) and continue beating until it holds soft, pillowy peaks. Do not overbeat – it should not be too stiff or grainy. Cover and keep filling chilled until ready to assemble.
Right before serving, mound the mascarpone cream onto the cake and gently spread it evenly.
Top with Fresh Raspberries (to taste), Fresh Strawberry (to taste), Blackberries (to taste), Fresh Blueberries (to taste) and Peach (to taste) and serve in slices. This can be made ahead of time and assembled up to 4 hours before serving. Keep covered in the refrigerator until ready to serve.