The Charge of the Cheese Brigade

I'm wading into the comfort food fray (again) with the actual recipe for the best mac & cheese ever, and yes, it's from Martha. But trust me - have I lied to you yet? That you know of? *blink blink*

Macaroni & Cheese
1/2 cup plus 1 tbsp unsalted butter
4 cups uncooked macaroni (obviously this is going to make a lot of mac & cheese)
5 cups milk
1/2 cup plus 1 tbsp flour
1 tsp salt
1/4 tsp fresh ground pepper
1/4 tsp cayenne pepper (or more to taste)
2 cups grated sharp yellow cheddar cheese
2 cups grated sharp white cheddar cheese
1 cup fresh grated parmesan
20 green onions (scallions), sliced white & green parts (I leave these out)
5 oz fresh goat cheese

1. Heat oven to 375 degrees & lightly butter a 2 quart casserole dish.
2. Cook macaroni until al dente, or not quite as long as package directs.. Drain, rinse in cold water and set aside.
3. Warm milk in a medium saucepan over medium low heat. Melt butter in a large (seriously, use a large one) heavy pot over medium heat. Make a roux: whisk in the flour gradually and cook for two minutes until the mixture is thick and smooth. Whisking constantly (this is important), slowly add the milk. Cook over medium-low heat, 8-10 minutes, whisking (keep it up.) Remove from heat; add salt, pepper and cayenne.
4. In a bowl, combine 1/4 cup of each of the grated cheeses. Set aside, along with 1 tbsp onions (if using). Add remaining grated cheeses - not the goat cheese - to the warm white sauce. Stir well. Stir in remaining onions and cooked noodles. Add goat cheese in one-inch pieces and fold gently to combine.
5. Transfer mixture to prepared casserole. Top with reserved scallions and cheeses. Bake until golden brown and bubbling, 30-35 minutes.