01 -
Measure out ingredients prior to beginning. Place the sour cream near the stove for better melting. Shred the cheese from a block for better melting. Preheat the oven to 375°F.
02 -
Season ground beef with salt and pepper. Cook and crumble on medium-high heat for 2 minutes. Add onions and cook until the beef is fully cooked, about 3 more minutes. Drain the grease, add garlic, and cook for 1-2 minutes.
03 -
Stir butter into the skillet until melted. Sprinkle flour and mix to combine. Cook for 2 minutes until the flour no longer smells raw. Gradually add beef broth, stirring continuously. Use a silicone spatula to scrape fond from the pan for flavor. Bring to a boil, reduce to low heat, and mix in sour cream, Worcestershire sauce, mustard, frozen peas, and half the cheese.
04 -
Boil the pasta for 1 minute less than al dente, according to package instructions. Drain and mix into the sauce.
05 -
If the skillet is not oven-safe, transfer the mixture to a greased 9x13-inch casserole dish. Top with remaining cheese. Cover and bake for 20 minutes. Garnish with parsley before serving.
06 -
Boil noodles to full cooking time. Mix with sauce, top with cheese, cover, and cook on the stovetop until the cheese is melted.