Ground Beef Spinach Casserole

 for 6

• 1 pound ground beef
• 1 medium onion, chopped
• 1 clove garlic, minced, or more to taste
• 1 (10-ounce) can sliced mushrooms, drained
• 1 teaspoon dried oregano
• 2 dashes hot pepper sauce, or more to taste
• salt and ground black pepper to taste
• 2 (10-ounce) packages frozen chopped spinach, thawed and drained
• 1 (10.5 ounce) can condensed cream of celery soup
• 1 cup sour cream
• 1 (8-ounce) package shredded mozzarella cheese

1. Preheat the oven to 350 degrees F (175 degrees C).
2. Heat a large skillet over medium-high heat. 
3. Add ground beef, onion, and garlic; cook and stir in the hot skillet until beef is browned and crumbly, 5 to 7 minutes. 
4. Drain and discard grease. 
5. Add mushrooms, oregano, hot sauce, salt, and pepper; simmer for 5 minutes.
6. Add spinach, condensed soup, and sour cream; cook until heated through, about 5 minutes. 
7. Transfer mixture to a casserole dish and cover with mozzarella cheese.
8. Bake in the preheated oven until cheese is melted, 15 to 20 minutes.