Created by KittenCal on December 21, 2011
Step 1: Set oven to 350 degrees F. Grease a 13 x 9 baking pan.
Step 2: Cook the pasta only to firm-tender (don't overcook, as the pasta will cook more when baked in the oven, omit the salt in the water) drain, set aside.
Step 3: In a heavy-bottomed saucepan, melt the butter over med-high heat. Add in the chopped onion and garlic; saute for about 3 minutes. Whisk in the flour, thyme, nutmeg and black pepper; cook for 2 minutes, stirring constantly. Gradually whisk in the half and half; cook for 4 minutes, until thick and bubbly.
Step 4: Add in the grated Swiss cheese, and the Parmesan cheese; mix well over low heat, until the cheese has melted, and the sauce is hot and bubbly; remove the saucepan from the heat.
Step 5: In a large bowl, combine the cream/cheese sauce, 1/2 cup of the remaining Swiss cheese (it is not necessery to add the remaining 1/2 cup cheese, you may omit if desired), chopped tomato, and the spinach; stir well. Spoon the mixture into a prepared greased baking pan.
Step 6: For topping; In a small bowl, combine the breadcrumbs, melted butter and the Parmesan cheese; sprinkle the mixture over the casserole in the baking pan. Bake for 30 minutes, or until hot and bubbly.