Instructions:
Preparation time: 50 minutes  Cook time: 30-40 minutes  

Combine topping ingredients in a small bowl. Set aside.
 
In a large skillet, melt 2 tablespoons of butter over medium heat. Stir in onions and shallots and sauté until onions are soft and have caramelized to a rich golden-brown, about 30 minutes. Mixture should cook down to ½ cup. Remove from pan and set aside.  

Place rack in center of oven. Preheat oven to 375°F. Lightly butter a 9 x 13 inch baking dish. In a large pot, bring 4 quarts of water to a boil. Add 1 tablespoon salt and pasta. Cook according to package directions, stirring occasionally. Pasta is done when it is slightly chewy to the bite or al dente. Drain pasta in a colander and set aside.  

Melt remaining 6 tablespoons of butter over medium heat in a large heavy saucepan. Whisk in flour and cook 3 minutes, whisking constantly. Gradually add milk and bring just to a boil, whisking constantly. Reduce heat and simmer, whisking often until sauce slightly thickens, about 2 minutes. Add salt and mascarpone and whisk until smooth.  Keep warm.  

In a large bowl, combine 1/3 of sauce, Vintage White Extra Sharp Cheddar Cheese, green onion, garlic, thyme, spinach, bacon, pepper and 1/3 of reserved pasta. Spread mixture evenly into prepared baking dish. Using the same bowl, combine half of remaining sauce, the Swiss and Jack cheeses, caramelized onion mixture and half of remaining pasta. Spread mixture  evenly over spinach mixture. Using the same bowl, combine the remaining sauce, Colby and Medium Cheddar cheeses, red onion, sun-dried tomatoes, cayenne pepper and the remaining cooked pasta. Spread mixture evenly over onion mixture. Top with reserved cracker topping. Bake for 30 – 40 minutes until cheese is bubbling and top is browned. Let sit 5 minutes before serving.

Serves 8-10