Preheat oven to 325 degrees. Butter a shallow 2 quart baking dish.

Cut slices of bread into small pieces and add to the bowl of a food processor. Pulse a few times to make coarse crumbs; you should end up with 1 cup. Set aside.

Cut onion into quarters. Take one quarter and stick it with the two cloves. In a small saucepan, combine milk and the onion stuck with cloves. Warm over medium heat and bring to a simmer. Remove from heat and set aside for 10-15 minutes.

Meanwhile, cut the remaining onion into thin strips. Heat a medium sauté pan over medium heat and add the onion to the dry pan. Cook until the onion becomes brown in color. Add ¼ cup water and cook until the water has evaporated. Remove onions from heat and set aside.

In a medium saucepan over low heat, melt the butter. Using a whisk, stir in the flour and cook, stirring constantly, for 30 seconds. Do not allow the mixture to brown. Remove from heat. Use a slotted spoon to remove the onion from the milk and discard. Gradually pour the milk into the flour mixture, stirring until combined. Return to heat and slowly bring to a boil, stirring constantly until the sauce thickens and is smooth – approximately 4-5 minutes. Add ½ cup of the cheddar cheese and all of the gorgonzola cheese. Stir until blended. Add salt and pepper to taste, finish with a sprinkle of nutmeg. Remove from heat and keep warm.

Bring a large pot about three-quarters full of water to a boil. Add the macaroni and cook until slightly underdone, approximately 6-8 minutes. Drain well.

Place the macaroni in an even layer in the bottom of the prepared dish. Add the bacon and caramelized onions over the top of the pasta. Spoon the sauce evenly over everything and then scatter the remaining shredded cheddar cheese and bread crumbs on top. Bake until lightly brown and bubbling, approximately 25-30 minutes. Serve immediately.