Whisk flour, 1 cup cornmeal, sugar, baking powder, salt, and garlic powder together in a bowl. Mix Cheddar cheese into dry ingredients until coated.
Beat milk, eggs, vegetable oil, jalapeno peppers, and vanilla extract together in a separate bowl until well mixed. Make a well in the Cheddar cheese mixture and pour egg mixture into the well; stir just until combined. Batter should be slightly lumpy.
Brush 18 mini muffin cups with melted butter; spoon about 1 teaspoon cornmeal into each mini muffin cup, tilt pan to coat muffin cups with cornmeal, and tap out the excess. Spoon batter into each muffin cup to about 2/3 full.
Bake in the preheated oven until lightly browned, 11 to 12 minutes. Allow to cool 5 minutes in the pans before removing to finish cooling.
