In a liquid measuring cup or medium bowl, whisk the eggs and milk until well-combined.
In a large bowl, add the flour, cornmeal, salt, baking powder, and baking soda, and whisk to combine.
Make a well in the center of the dry ingredients, then pour in the wet ingredients and whisk until smooth. Add the melted butter and stir to combine.
Grease a 9x13-inch (23x33-cm) glass baking dish with nonstick spray and line with parchment paper.
Pour the cornbread batter into the pan, smoothing the top with a spatula.
Bake for 25 minutes, or until a toothpick comes out clean. Let cool for about 10 minutes.
In a large pan, heat the olive oil over medium heat. Add the onion and cook until softened, stirring frequently, about 5 minutes.
Add the ground beef and break apart with a wooden spoon into small pieces. Add the salt, pepper, paprika, garlic powder, chili powder, and cumin. Cook, stirring frequently, until the ground beef is cooked through, about 5 minutes.
Add the crushed tomatoes and stir. Simmer for 10 minutes.
Using the bottom of a utensil with a handle that is about 1-inch (2 cm) in diameter, poke multiple holes in the cornbread.
Pour the chili over the cornbread and smooth the top with a spatula. Sprinkle the cheese over the chili.
Bake for 3 minutes, or until the cheese is melted.
Slice and serve with sour cream, scallions, and cilantro.