Pioneer Woman's Macaroni & Cheese

I'm adding this one to the Macaroni & Cheese Project list! This turned out really good; however, still not my favorite! It was creamy and flavorful, but I prefer to use more than one type of cheese. I'd say four out of five stars.

Ingredients
4 cups dried macaroni
1 whole egg
1/2 stick (4 tablespoons) butter
1/4 cup all-purpose flour
2 1/2 cups whole milk
2 heaping teaspoons dry mustard (more if desired)
1 pound sharp Cheddar, grated (not pre-grated cheese), plus more for baking
Salt
Seasoned salt
1/2 teaspoon ground black pepper
Optional spices: cayenne pepper, paprika, thyme

Directions
Preheat the oven to 350 degrees F.

Cook the macaroni until still slightly firm. Drain and set aside.

In a small bowl, beat the egg. In a large pot, melt the butter and sprinkle in the flour. Whisk together over medium-low heat. Cook for a couple of minutes, whisking constantly. Don't let it burn. Pour in the milk, add the mustard and whisk until smooth. Cook until very thick, about 5 minutes. Reduce the heat to low.

Take 1/4 cup of the sauce and slowly pour it into the beaten egg, whisking constantly to avoid cooking the eggs. Whisk together until smooth. Pour the egg into the sauce, whisking constantly. Stir until smooth. Add in the cheese and stir to melt. Add 1/2 teaspoon salt, 1/2 teaspoon seasoned salt and the pepper. Add any additional spices if desired. Taste the sauce and add more salt and seasoned salt as needed! DO NOT UNDERSALT.

Pour in the drained, cooked macaroni and stir to combine. Serve immediately (while it's still very creamy) or pour into a buttered baking dish, top with extra cheese and bake until bubbly and golden on top, 20 to 25 minutes.