Set your oven to 375°F (190°C) right away.
Line your muffin tin with paper liners now.
This prevents the muffins from sticking later.
Combine flour, cornmeal, and sugar in a bowl.
Add baking powder and salt to the mixture.
Whisk everything together until well combined.
Crack eggs into a separate bowl first.
Add milk, melted butter, and vanilla extract.
Whisk until the mixture is smooth and combined.
Pour wet ingredients into the dry mixture slowly.
Stir gently until just combined together.
Don't overmix or muffins will be tough.
Fold raspberries into the batter very carefully.
Be gentle so they don't break apart.
Some will break, and that's perfectly okay.
Scoop batter into prepared muffin cups evenly.
Fill each cup about three-quarters full.
Bake for 20-25 minutes until golden brown.
Insert a toothpick to check for doneness.
Let muffins cool in the pan for 5 minutes.
Transfer them to a wire rack afterward.
Serve warm with butter or eat them plain.