Preheat the oven to 425°F. Grease and flour a 12 cup muffin pan and set aside.
In a medium bowl, whisk together the flour, baking powder, sugar, salt, and Mexican spice blend. (If you don't have Mexican spice blend, use a packet of taco seasoning.)
1 ½ cups all-purpose flour, 1 ½ tablespoon baking powder, 1 tablespoon sugar, 1 teaspoon Mexican spice blend, ½ teaspoon salt
Whisk the milk, egg, and melted butter together in a small bowl.
1 cup milk, 1 large egg, ¼ cup unsalted butter
Pour the milk mixture into the dry ingredients and stir to incorporate.
Before the mixture is entirely mixed, add the Mexican cheese blend and chopped jalapeno. Stir to make sure that the mixture is evenly moistened and the cheese is well distributed.