To make the cornbread, preheat the oven to 375˚F. Spray an 8x8-inch baking pan with nonstick cooking spray.
Beat the eggs in a medium bowl with a whisk. Whisk in buttermilk. Set aside.
In a large bowl, whisk together cornmeal, flour, sugar, baking powder, and salt. Add the egg mixture to the dry ingredients, stirring until they are combined. Stir in melted butter and green chiles.
Add the batter to the baking dish. Bake for 25 minutes, until golden brown. Cool the cornbread completely.
Once the cornbread is cooled, dice the cornbread into medium cubes. Let the bread sit out at room temperature for up to one day before making the stuffing.
When you are ready to make the stuffing, preheat oven to 350˚F. Spray a 2-quart baking dish with nonstick cooking spray.
Heat a large skillet over medium-high heat. Once hot, add onion, green onion, and garlic. Cook, stirring occasionally, until the onion is browned and softened, about 10 minutes.
Stir in the corn and cilantro. Season to taste with salt and pepper.
Toss the cornbread with the beaten egg and chicken stock gently. Carefully fold in the onion mixture until well combined. Add the mixture to the prepared baking pan.
Bake for 25 minutes, until the top is golden brown.