Preheat your oven to 350°F (175°C) and prepare a muffin tin with cupcake liners.
In a bowl, whisk together the flour, baking powder, and salt.
In another bowl, cream together the softened butter and sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
Alternate adding the dry ingredients and milk to the butter mixture, starting and ending with the dry ingredients.
Gently fold in the mixed berries.
Divide the batter evenly into the prepared cupcake liners.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted comes out clean.
Let the cupcakes cool in the tin for 5 minutes before transferring to a wire rack.
While cupcakes cool, whip the heavy cream with powdered sugar until soft peaks form.
Once the cupcakes are completely cool, pipe or spread the whipped cream on top.
Garnish with fresh berries and mint leaves before serving.
