Heat the oven to 350°F and lightly grease a 9-by-13-inch baking dish. Keep the Texas toast frozen until you are ready to assemble the casserole so the slices hold their shape and brown properly.

Place the lean ground beef and diced onion in a large skillet over medium heat. Cook while breaking the beef into small crumbles until the meat is browned and the onion is tender.

Add the minced garlic during the final minute of browning. Stir constantly just until fragrant, taking care not to let the garlic burn.

Drain the excess fat from the skillet. Removing extra fat helps keep the finished toast from becoming greasy or soft.

Stir the tomato soup, cream of mushroom soup, drained green beans, salt, and black pepper into the beef mixture. Heat and stir until the ingredients are evenly combined and the filling is warm.

Arrange the eight frozen Texas toast slices in a single layer in the prepared baking dish. Spoon the beef-and-soup mixture evenly over the toast, covering as much of the surface as possible.

Sprinkle the shredded cheddar evenly over the filling. An even layer helps every portion receive melted cheese and keeps the casserole balanced from edge to edge.

Bake the casserole uncovered for about 20 to 25 minutes, until the filling is hot, the cheese is melted, and the toast is crisp around the edges. If needed, bake for 5 minutes longer, then let the casserole rest briefly before serving.