Berry Chantilly Cupcakes

Preheat the oven to 350℉ (177℃). Line cupcake pans with 14 cupcake liners.
In a small mixing bowl, whisk together the cake flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or in a large mixing bowl with an electric hand mixer, cream the granulated sugar, unsalted butter, and vegetable oil until it is smooth and creamy. Add in the egg whites, sour cream, vanilla extract, and vanilla bean paste and mix until well combined.
Add half of the flour mixture to the mixing bowl and mix on low speed until mostly combined. Then, add in the milk and mix on low speed until mostly combined. Add the remaining flour mixture and mix the cupcake batter on low speed until fully combined and smooth.
Portion the cupcake batter into the cupcake liners using a large cookie scoop (about ⅔ full). Bake the cupcakes for 20 minutes until the cupcakes are puffed up and they bounce back when gently touched. Cool the cupcakes in the pan for 5 minutes and then transfer to a wire rack to cool completely.

In the bowl of a stand mixer fitted with a whisk attachment or in a large mixing bowl with an electric hand mixer, cream the mascarpone cheese, powdered sugar, and vanilla extract until smooth and creamy.
While mixing on low speed, slowly drizzle in the heavy whipping cream until the ingredients are well combined and smooth. Scrape the sides and bottom of the bowl.
Increase the mixer speed to medium-high and whip the frosting for a few minutes until medium-stiff peaks form. (The frosting will hold its shape, but still remain soft).

In a small saucepan, combine the frozen mixed berries, granulated sugar, and lemon juice. Place the saucepan over medium heat to cook the berry mixture, stirring occasionally, for 10 minutes until the berries break down and the mixture is bubbling. Use a wooden spoon to break up the berries.
In a small bowl, stir together the cornstarch and water to create a slurry. Remove the saucepan from the heat and add in the cornstarch slurry while stirring well to thicken the berry filling.
Transfer the berry filling to a heat-safe container and cool to room temperature. Chill in the refrigerator for at least 2 hours before filling the cupcakes to thicken the filling.

Use an apple corer/cupcake corer to remove the center of the vanilla bean cupcakes. Fill a piping bag with the tip cut off with the mixed berry filling. Pipe the filling into the center of the cored cupcakes.
Fill a piping bag fitted with a Wilton 1M piping tip with the chantilly cream frosting. Pipe a generous swirl of frosting onto the filled cupcakes. Decorate the cupcakes with fresh strawberries, raspberries, and blueberries.

Storing & Serving:

Store the cupcakes in an airtight container in the refrigerator for 2 to 3 days.
Serve the cupcakes chilled for the best taste and texture.

Helpful Tips:

Make the mixed berry filling up to a week in advanced. The filling needs to chill for at least 2 hours, so I recommend making it ahead of time.

Note: Metric conversions and nutritional information are calculated automatically. I cannot guarantee the accuracy of this information.