Preheat oven to 350 degrees.

In a large bowl, stir together flour, sugar, baking powder and salt. Add butter, eggs, milk and vanilla extract and beat until mixed well. Transfer batter into lined muffin cups, leaving 1/2" of space to the top.

Bake in preheated oven for 16 - 20 minutes, until an inserted toothpick comes out clean. Allow to cool, and top with mascarpone cream frosting, and top with sliced strawberries and blueberries.

In a large bowl, add mascarpone cheese, heavy whipping cream, sugar and vanilla extract, and beat until frosting thickens up and stiff peaks form.