Brown hamburger in a large skillet with minced onion and drain off any excess grease.

Add cut green beans, cream of mushroom soup, salt, and pepper to the skillet.

Stir the mixture until well combined.

Simmer the mixture on low heat.

In a separate bowl, prepare the Jiffy Corn Muffin Mix according to the package instructions, combining the egg and milk with the mix.

Lightly spray an 8 x 8 inch casserole dish with cooking spray.

Transfer the hamburger mixture into the prepared casserole dish.

Evenly spread the cornbread batter over the hamburger mixture.

Cook in microwave, uncovered, on high heat for 10 minutes.

Let cool slightly before serving.