For the cupcakes

1. Preheat the oven to 350°F. Line a cupcake pan with cupcake liners.
2. In a large mixing bowl, combine the sugars, vegetable oil, butter, eggs and egg yolks and vanilla extract. Beat on medium speed until the eggs and oil are well incorporated and the batter is lighter in color, about 2 minutes. Scrape down the bowl as needed. Next mix in the sour cream and beat until well combined.
3. In a separate bowl, combine the remaining dry ingredients. Alternate adding half the dry ingredients and half the milk at a time and mix just until the flour starts to incorporate. Use a spatula to scrape down the sides of the bowl and stir the batter from the bottom to the top to ensure it’s well mixed.
4. Using a large cookie scoop, divide the batter evenly, filling each liner 2/3 full. Bake at 350°F for 14-16 minutes. Test the cupcakes for doneness by inserting a toothpick into the center of the cupcake. If the toothpick comes out clean, the cupcakes are done. Cool Completely.

For the crumble topping

1. While the cupcakes are baking, prepare the topping. In a bowl, combine all the ingredients. Whisk the dry ingredients together and then add the melted butter. Stir until there are no dry crumbs left. Mixture should be crumbly. If it’s too dry add another ½ tablespoon melted butter.
2. Spread the crumble topping on a baking sheet lined with parchment paper or a silicone baking mat. Once the cupcakes are done, bake for 8 minutes. Remove from the oven and cool completely.

For the filling

1. Empty the filling into a bowl. Take a spoon with one hand to hold the sliced peaches, and then cut the peaches into small pieces with a pair of kitchen scissors.

For the frosting

1. Place the mixing bowl and whisk attachment in the freezer for 5 to 10 minutes to chill. Spoon the cold mascarpone cream into your bowl and beat on a medium-low speed. Slowly pour in the heavy cream, allowing the mascarpone cheese to turn to a liquid consistency. Then increase the mixing speed to high and beat it until soft peaks form.
2. Next, add the powdered sugar and vanilla extract, beating on low until sugar is incorporated. Then continue beating at a high speed until stiff peaks form.

To assemble the cupcakes

1. Remove the centers using a cupcake corer or a Save the tops of the cupcakes to the side.
2. Use a spoon to fill the center of each cupcake with the peach filling. Gently push the top of the cupcake back on top of the filling.
3. Use a large piping tip to frost the cupcakes. Garnish with crumble topping.