Prepare pasta according to package directions. Drain. Do not rinse. Put pasta in a large bowl.

Season ground beef with salt, pepper, and Worcestershire sauce as desired. Scramble in skillet until done, remove from heat, drain off grease.

Make the cheese sauce:

In a saucepan, melt butter over medium heat. Add flour and cook until it just starts to brown. Reduce heat.

Whisk in milk a little at a time until all milk is added and sauce is smooth.

Add 2 cups shredded cheese to sauce, a little at a time, stirring until cheese is melted. For a more cheesy sauce, you can add additional cheese. If the sauce gets too thick, stir in a little more milk.

[For a shortcut cheese sauce, skip steps 4-6 and do this instead: In a saucepan, melt 2 tablespoons of butter over low heat. Add half a cup of milk and half a box of Velveeta, cut into small chunks. Cook over low heat, stirring constantly, until Velveeta is melted. Add extra shredded cheese, if desired, and stir until melted. Add extra milk, if needed, to bring sauce to desired consitency.]

Add ground beef and any desired mix-ins (bacon, onions, etc.) to cheese sauce and stir until mixed in well.

Pour cheese sauce mixture over cooked pasta. Toss until pasta is well-coated with cheese sauce and other ingredients are evenly mixed in.

Put pasta mixture into a large, oven-proof casserole dish or pan. Top with shredded cheese and bread crumbs, if desired. (Or you could divide the mixture between loaf pans before topping.)

Bake at 350°F for about 30 minutes or until the cheese is melted and bread crumbs are browned. Let cool slightly before serving.