Cook the listed bacon until crisp, drain it, and chop it. Position the oven rack in the center and preheat to 350°F. Generously grease a 9×13-inch baking dish. Reserve the topping portions of bacon and cheese before mixing.
In a large mixing bowl, whisk together the cornmeal, flour, baking powder, salt, and sugar until evenly combined.
Add the thawed corn, milk, and sour cream to the bowl with the dry ingredients. Gently stir the mixture to combine, making sure there are no dry spots.
Pour in the melted butter, add a sprinkle of freshly ground black pepper, and fold in most of the bacon, jalapeños, and 1 cup of cheddar cheese. Mix until just combined. Be careful not to overmix, as this can make the casserole dense.
Pour the cornbread mixture into the prepared baking dish, using a spatula to spread it evenly.
Bake in the preheated oven for 40 to 45 minutes, or until the top is lightly golden and a toothpick inserted in the center comes out clean.
Remove the casserole from the oven and sprinkle the remaining bacon, ½ cup of cheddar cheese, and green onions, if using, on top. Return to the oven for about 3–5 minutes, just until the cheese melts. Rest for about 5 minutes before serving.
Let the casserole cool for a few minutes, then serve it warm.