In a skillet over medium-high heat, add the ground beef and cook until fully browned, then drain any excess liquid. Next, combine the refried beans, chopped onion, minced garlic, ½ cup of the tomato sauce, chili powder, oregano, cumin, and salt and pepper to taste with the meat in the skillet. Cook for an additional 5 minutes over medium heat, stirring well to mix the ingredients.

Warm the tortillas in the microwave until they’re soft and pliable. In a deep skillet, pour about an inch of oil and heat it over medium-high heat on the stove.

Take an even portion of the filling and place it in the center of each tortilla. Fold one end of the tortilla over the filling, tuck in the sides, and roll it closed to form a packet, securing it with a toothpick.

Carefully place the filled chimichangas in the hot oil and fry until they are golden brown and crispy on both sides, keeping a close watch as this won't take long. Once done, drain the excess grease by letting them cool on a paper towel-lined tray.

In a saucepan over medium heat, pour in the remaining tomato sauce, green chiles, and jalapeño peppers, warming the sauce through. Adjust seasoning with salt and pepper if necessary.

Ladle the warm sauce over the cooked chimichangas, top with shredded cheese, and serve.