Preheat oven to 350°F. Grease a rectangular glass casserole dish.

Cook macaroni in salted water according to package directions until al dente. Drain well and let cool for a few minutes.

Transfer the cooked macaroni to the prepared casserole dish and toss with the beaten egg.

In a medium saucepan over medium-low heat, melt the butter and whisk in the flour until you have a smooth paste (roux).

Pour in the half-and-half and bring the mixture to a gentle boil, stirring constantly.

Reduce heat and add the Velveeta and cream cheese chunks. Stir until melted and smooth.

Season the sauce with Worcestershire sauce, dry mustard, salt, and pepper, stirring until everything is well combined. The sauce should coat the back of a spoon.

Pour the cheese sauce over the macaroni and egg mixture, then sprinkle with parmesan cheese. Stir to ensure all noodles are coated.

Bake for 25-30 minutes until bubbly and slightly golden on top.

Let rest for about 5 minutes before serving to allow the sauce to set.