Preheat oven to 375°F. Place 1 Tbsp butter in a 10-inch cast iron skillet and into the oven while it preheats. (Melt the remaining 7 Tbsp butter in a microwave safe bowl for the batter.)
In a medium bowl use a whisk to sift together cornmeal, flour, sugar, baking powder, salt, baking soda and garlic.
In a separate bowl whisk together buttermilk, melted butter and eggs.
Add the wet ingredients to the dry ingredients mixing until fully moistened.
Use a large spatula to mix in 1 cup cheddar cheese, diced jalapeno and green onions. Stir to evenly distribute.
Remove skillet from oven and swirl to coat the bottom and sides with butter. Pour cornbread batter evenly into the pan. Sprinkle with the remaining 1 cup shredded cheddar cheese.
Bake for 25-30 minutes or until a toothpick inserted into the center comes back clean.