Ham and Cheddar Lunch Box Muffins

1 1/2 cups all-purpose flour
1/2 cup stone-ground yellow cornmeal
2 teaspoons baking powder
1 teaspoon garlic powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 1/4 cups buttermilk
2 large eggs
7 tablespoons unsalted butter, melted and cooled, divided
1 cup shredded sharp cheddar cheese
8 ounces thick-cut deli ham (1/2-inch thick), diced
3 tablespoons finely chopped chives, divided
Freshly ground black pepper

Arrange a rack in the middle of the oven and heat to 375°F. Line a standard 12-well muffin pan with papers liners or coat the wells with cooking spray. Whisk together the flour, cornmeal, baking powder, garlic powder, baking soda, and salt in a large bowl. Whisk the buttermilk, eggs, and 5 tablespoons of the butter in a medium bowl until combined. Pour the wet ingredients into the dry and mix with a wooden spoon or rubber spatula until just combined. Some lumps are fine. Fold in the cheese, all but 1/2 cup of the ham, and 2 tablespoons of the chives. Spoon the batter into the muffin wells, filling each about 3/4 full. Top the muffins with the reserved ham, sprinkle with the remaining chives, and sprinkle with pepper. Top each muffin with 1/2 teaspoon of the remaining melted butter. Bake until the tops just begin to brown, and a toothpick inserted in the center of a muffin comes out clean, 20 to 25 minutes. Cool the muffins in the pan for about 5 minutes, then transfer to a cooling rack to cool completely. RECIPE NOTES: Storage: Leftovers can be stored in an airtight container in the refrigerator for up to 4 days, or in the freezer for 3 months. Eat cold or reheat in the toaster oven for a few minutes before serving.