01 - Preheat oven to 350°F. Lightly grease a 12-cavity donut pan with butter or nonstick spray.
02 - In a large mixing bowl, whisk together all-purpose flour, granulated sugar, baking powder, baking soda, and salt until evenly blended.
03 - In a separate bowl, blend cream soda, whole milk, melted butter, eggs, and vanilla extract until smooth.
04 - Gently fold the wet mixture into the dry ingredients until just combined. Avoid overmixing to preserve donut tenderness.
05 - Transfer batter to a piping bag or large zip-top bag. Pipe the mixture evenly into the prepared donut pan, filling each cavity about two-thirds full.
06 - Bake for 10 to 12 minutes, or until donuts spring back lightly when touched and a toothpick inserted comes out clean.
07 - Allow donuts to cool in the pan for 5 minutes. Then transfer carefully to a wire rack and let cool completely.
08 - Whisk powdered sugar with cream soda, adding 1 tablespoon at a time until the glaze is thick yet pourable. Stir in vanilla extract and rainbow sprinkles.
09 - Dip the tops of cooled donuts into the glaze, letting excess drip off. Immediately garnish with extra sprinkles.
10 - Leave glazed donuts at room temperature for 15 to 20 minutes to allow glaze to set before serving.