Line your baking tray with liners and keep them aside depending on what muffin pan or silicone liners you are using. Or spray them with cooking spray.
In a large bowl, sift the 1 cup all-purpose flour, 1 teaspoon baking powder, and 1/2 teaspoon salt and keep aside.
In another bowl, whisk the 1/3 cup unsalted butter and 1/2 cup granulated sugar together till it's light and creamy. Add in 1 large egg and 1/4 teaspoon vanilla extract and mix well. Add the flour mixture and 1/4 cup milk in batches alternatively to the butter mixture. Add the 1/4 cup fresh blueberries and mix well.
Fill your liner up to 3/4 with the batter and bake for 10 to 12 minutes, at 320 degrees F, air fryer setting, or till the toothpick inserted in the middle comes out clean. Once baked, let them cool completely before topping them with frosting.
In a large bowl, cream the 1/2 cup unsalted butter for 1-2 mins till it's light and creamy. Add the 1 cup powdered sugar in batches and keep mixing.
Then add the 4 tablespoons pureed blueberries and mix and decorate your cupcakes as you like.
Plate, serve, and enjoy!