Step 1

Measure out ingredients prior to beginning.Place the sour cream near the stove while you cook. It will melt better into the sauce if it's closer to room temperature.If possible, shred the cheese from a block (it melts much better than from a bag).Preheat oven to 375°.

Step 2

Season the ground beef with salt and pepper. Cook and crumble it on medium-high heat for 2 minutes. Add the onions and cook until the ground beef is cooked through, about 3 more minutes.

Step 3

Drain any grease, then add the garlic and cook for 1-2 minutes.

Step 4

Stir in the butter until melted. Sprinkle on the flour and mix to incorporate. Cook for 2 minutes or until you can no longer smell flour.

Step 5

Add the beef broth in splashes, stirring continuously. Don't add too much at once. Use a silicone spatula to clean the "fond" from the pan, this will give the sauce plenty of flavor.

Step 6

Bring to a boil, then reduce heat to low. Add in the sour cream, Worcestershire sauce, mustard, frozen peas, and *half* of the cheese. If the sour cream doesn't melt well right away, it will eventually incorporate into the sauce, stirring will help.

Step 7

Let the sauce simmer on low while you boil the pasta for 1 minute less than al dente (refer to package for time). Drain and add the pasta to the sauce. Stir to combine.

Step 8

If your skillet is not oven safe, transfer it to a lightly greased 9 x 13-inch casserole dish.

Step 9

Top with remaining cheese. Cover and bake for 20 minutes. Sprinkle with fresh parsley and serve!

Step 10

Note: To cook fully on the stovetop, boil noodles for full amount of time, add to the sauce, top with cheese, and cover the pot until the cheese is melted.