01 - Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup with nonstick spray.
02 - In a large mixing bowl, whisk together all-purpose flour, yellow cornmeal, granulated sugar, baking powder, and salt until evenly mixed.
03 - In a separate bowl, whisk whole milk, eggs, melted unsalted butter, and vanilla extract until thoroughly combined.
04 - Add the wet mixture to the dry ingredients and stir gently with a spatula until just combined. Avoid overmixing to maintain tenderness.
05 - Fold in the rainbow sprinkles gently, ensuring even distribution throughout the batter.
06 - Spoon the batter evenly into each of the prepared muffin cups, filling them about three-quarters full.
07 - Bake for 16 to 18 minutes, or until a toothpick inserted in the center of a muffin emerges clean.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely before serving.