Preheat the oven to 350°F (175°C). Lightly grease a 10-cavity donut pan or, if making bite-sized versions, a mini muffin tin. Properly greasing the pan helps the donuts release cleanly and maintain their shape.
Make the Donut Batter
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, granulated sugar, and freeze-dried strawberry powder. Make sure the strawberry powder is evenly dispersed to avoid streaks of concentrated flavor and to create a consistent pink hue throughout the batter.
In a separate bowl, whisk the sour cream, buttermilk, egg, melted butter, and vanilla extract until smooth. The mixture should appear creamy and cohesive, which helps the dry ingredients blend more evenly once combined.
Add the wet mixture to the dry ingredients and gently fold together with a spatula. Mix only until no streaks of flour remain. Overmixing can lead to dense donuts, so stop as soon as the batter comes together.
Prepare the Cheesecake Swirl
Beat the softened cream cheese, sugar, sour cream, and vanilla until fully smooth and fluffy. The mixture should have no lumps and be easily pipeable. Transfer it to a piping bag or a resealable plastic bag with the corner snipped.
Assemble the Donuts
Fill each donut cavity about ¾ full with the strawberry batter. Leave enough space for the donuts to rise without spilling over.
Pipe about 1 teaspoon of the cheesecake mixture into the center of each cavity. Use a toothpick to gently swirl it into the batter, creating a marbled effect without fully mixing the layers.
Bake
Bake for 10–12 minutes, or 9–10 minutes for mini donuts, until the tops spring back lightly when touched or a toothpick inserted into the edge comes out clean. Allow the donuts to cool in the pan for about 5 minutes to firm up before transferring them carefully to a wire rack.
