Start by melting your butter on medium-high heat. Once melted, add in the shallots and garlic, and cook for about 4 minutes, stirring along the way.
Preheat your broiler to 425 degrees.
Next add in the half and half, and stir. Add in the crab meat, and continue to stir. Once the sauce comes to a simmer, add in the cheeses and let them melt. Once melted, add in the cooked bacon, and the cooked pasta. Stir, and cook until the sauce thickens and completely coats the pasta.
Remove and place into a baking dish. Top with the panko bread crumbs, and place under the broiler until they get nice and golden brown. Remove, and serve.