Preheat your oven to 400°F (200°C) and line a muffin pan with paper liners.

In a large mixing bowl, whisk together the cornmeal, flour, baking powder, and sugar until fully combined.

In another bowl, whisk the buttermilk, eggs, and melted butter until smooth.

Gradually pour the wet mixture into the dry ingredients, stirring gently until just combined.

Fold in the chopped jalapeños and, if using, the cheese.

Spoon the batter into the muffin cups, filling each about two-thirds full.

Bake for 15-20 minutes or until golden brown on top and a toothpick comes out clean.

Let the muffins cool for about 5 minutes before transferring them to a wire rack.