01 - Preheat oven to 375°F. Grease a 12-cavity donut pan generously and set aside.
02 - In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt until evenly distributed.
03 - In a separate bowl, whisk together the whole milk, eggs, melted unsalted butter, and vanilla extract until smooth.
04 - Pour the wet ingredient mixture into the dry ingredients. Stir gently with a spatula until just combined. Be careful not to overmix, as this can produce dense donuts.
05 - Transfer the batter into a piping bag or a zip-top bag with a corner snipped off. Pipe the batter evenly into each cavity of the prepared donut pan, filling about three-quarters full.
06 - Bake for 10 to 12 minutes, or until the donuts are lightly golden and a toothpick inserted into the center comes out clean. Allow to cool in the pan for 5 minutes, then transfer to a wire cooling rack to cool completely.
07 - Using an electric mixer, beat the room-temperature butter on medium speed until creamy and pale, about 2 minutes. Gradually add the sifted powdered sugar, beating on low until incorporated, then increase to medium-high until smooth.
08 - Add the strawberry puree, vanilla extract, and a pinch of salt to the buttercream. Beat on medium-high speed until light and fluffy, about 2 to 3 minutes. Adjust consistency with additional powdered sugar for stiffness or a splash of milk to thin.
09 - Once the donuts are completely cool, spread or pipe the strawberry buttercream generously over each donut. Top with freeze-dried strawberry pieces or sprinkles as desired.