01 - Preheat oven to 350°F. Grease two 6-cavity donut pans 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 ingredients into the dry ingredients and fold gently until just combined. Be careful not to overmix, as this can make the donuts tough.
05 - Spoon the batter into the prepared donut pans, filling each cavity about three-quarters full.
06 - Bake for 10 to 12 minutes, or until a toothpick inserted into a donut comes out clean and the tops spring back when lightly touched.
07 - Allow the donuts to cool in the pans for 5 minutes, then transfer them to a wire cooling rack to cool completely before frosting.
08 - Using an electric mixer, beat the softened butter on medium speed until creamy and pale. Gradually add the sifted powdered sugar, beating continuously until the mixture is light and fluffy.
09 - Add the strawberry puree, vanilla extract, and a pinch of salt to the buttercream. Beat on medium-high speed for 2 to 3 minutes until the frosting is smooth, light, and evenly colored.
10 - Once the donuts are completely cool, spread or pipe the strawberry buttercream generously over each one. Garnish with thinly sliced fresh strawberries or sprinkles as desired.