1 tablespoon olive oil
1 cup chopped onion
8 ounces 90% lean ground beef
3/4 teaspoon dried oregano
1 1/4 cups unsalted chicken stock
1/2 teaspoon salt
1/2 teaspoon black pepper
1 1/2 cups unsalted crushed tomatoes or tomato sauce
8 ounces uncooked whole-grain penne pasta
5 ounces fresh baby spinach
4 ounces preshredded part-skim mozzarella cheese (about 1 cup)
How to Make It
Preheat broiler to high. Heat oil in a large ovenproof skillet over medium-high. Add onion; sauté 2 minutes. Add beef and oregano; cook 3 minutes, stirring to crumble.
Add stock, salt, pepper, tomatoes, and pasta; bring to a boil. Cover, reduce heat, and simmer 12 to 13 minutes or until pasta is done. Stir in spinach.
Sprinkle cheese over pasta mixture. Place pan in oven; broil 2 minutes or until cheese melts and begins to brown.