Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a bowl, whisk together the flour, baking powder, and salt.
In another bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla extract.
Mix in the sour cream and milk until well combined.
Gradually add the dry ingredients to the wet mixture, stirring until fully incorporated.
Gently fold in the blackberries.
Divide the batter evenly among the cupcake liners and bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cupcakes to cool completely before frosting.
Decorate each cupcake with cream cheese frosting, a sprinkle of edible lavender, a few blackberries, and a raspberry on top. Enjoy!