1-Preheat oven: Preheat oven to 350 degrees F to get it ready for baking.

2-Heat a large oven-safe pot: Heat a large oven-safe pot over medium-low heat, add 4 tablespoons butter, then stir in 1 diced onion, 3 cloves garlic (minced), a pinch of salt and pepper; cook until the onions soften.

3-Cook pasta and prepare cheeses: Cook 1 pound short cut pasta separately according to package instructions; toss the grated cheeses (12 ounces fontina, 6 ounces white cheddar, and 2 ounces Parmesan) together.

4-Stir flour into onion mixture: Stir 4 tablespoons all-purpose flour into the onion mixture to create a roux, and cook for 2 to 3 minutes until golden and nutty smelling.

5-Add milk and nutmeg: Slowly add 2 ½ cups whole milk while stirring constantly until the mixture thickens; add ¼ teaspoon freshly ground nutmeg.

6-Add fresh spinach: Add 12 ounces fresh baby spinach; it will cook down quickly, and stir until soft.

7-Stir in cheese and pasta: Stir in most of the cheese mixture (reserving some for topping), then add the cooked pasta and combine well.

8-Top with remaining cheese and onions: Top with the remaining cheese and ½ cup crispy onions or breadcrumbs.

9-Bake: Bake for 30 to 35 minutes until golden and bubbly.