Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

In a large bowl, cream together the butter and sugar until light and fluffy.

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

Add the dry ingredients to the wet ingredients in three parts, alternating with the sour cream and milk, beginning and ending with the dry ingredients.

Mix until just combined. Gently fold in the raspberries and chopped pistachios.

Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full.

Bake for 18–20 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.

For the filling, mix together the raspberry jam and mascarpone cheese until smooth.

Once the cupcakes are completely cooled, use a small knife to cut out a small hole in the center of each cupcake. Fill each hole with the raspberry mascarpone mixture.

For the frosting, beat the butter until creamy. Gradually add the powdered sugar, vanilla extract, and heavy cream, beating until smooth and fluffy.

Frost the filled cupcakes and garnish with fresh raspberries and chopped pistachios.