Preheat the oven to 425° and butter the sides and bottom of a 9 x 9 inch non-stick baking pan. Set aside.
In a large mixing bowl, sift together the yellow cornmeal, all-purpose flour, baking powder, granulated sugar, garlic salt and ground cumin.
Add the shredded pepper-jack cheese, diced jalapeno and sweet onion. Mix until evenly distributed.
In a separate bowl, whisk together the eggs, buttermilk, cream corn and melted butter.
Add the wet ingredients to the dry ingredients. Mix until all of the ingredients are fully moistened.
Spread the batter evenly into the prepared pan. Bounce the pan on the counter a few times to settle the batter and release air bubbles.
Bake the cornbread for 30 minutes until the top is golden and a toothpick inserted into the center shows moist crumbs. Rest for 10 minutes before serving.