Spinach Beef Bake

Ingredients

• 1 pound ground beef
• 1 jar (4-1/2 ounces) sliced mushrooms, drained
• 1 medium onion, chopped
• 2 garlic cloves, minced
• 1-1/2 teaspoon dried oregano
• 1-1/4 teaspoon salt
• 1/4 teaspoon pepper
• 2 packages (10 ounces each) frozen chopped spinach, thawed and squeezed dry
• 1 can (10-3/4 ounces) condensed cream of celery soup, undiluted
• 1 cup sour cream
• 1 cup uncooked long grain rice
• 1 cup shredded part-skim mozzarella cheese