Preheat the oven to 350 degrees F. Line a loaf pan with parchment and grease a 6-cup muffin tin.
In a large bowl combine the ground beef, 3/4 cup Pepper Jack cheese, breadcrumbs, 1 egg, onion, jalapeno, garlic powder, salt, and black pepper. Mix until just blended. Press the mixture into the loaf pan.
In a small bowl stir together the ketchup, brown sugar, and Dijon mustard. Spread half the sauce over the meatloaf. Bake for 45 minutes.
While the meatloaf bakes, make the muffins. In a medium bowl whisk the cornmeal, flour, baking powder, and remaining 1/4 cup Pepper Jack cheese. In another bowl beat the remaining egg with the milk and melted butter. Pour the wet mixture into the dry ingredients and stir until combined. Spoon into the muffin tin. Add the muffins to the oven for the final 20 minutes of the meatloaf bake time.
Remove both from the oven. Let the meatloaf rest 5 minutes, then slice and serve with the remaining sauce on the side.