Preheat oven to 350 degrees F (about 177 degrees C). Grease the bottom and sides of a 3-quart baking dish with butter and set aside.
In a large saute pan, heat the olive oil over medium heat. Add the diced bacon and cook until golden brown. Remove with a slotted spoon to a plate lined with paper towels.
Add the garlic to the pan and cook until lightly golden brown. Whisk in the flour and cook for 1-2 minutes. Next, whisk in 6 cups of the hot milk, increase the heat to high, and cook, whisking constantly until thickened, for 3-5 minutes. Whisk in the light beaten egg yolks until incorporated and let cook for 1- 2 minutes, stirring constantly. Remove from heat and whisk in the chopped chives, cayenne, and all of the cheese until completely melted. Season with salt and pepper. If the mixture appears too thick, add some of the remaining milk 1/4 cup at a time.
Mix in the cooked macaroni, reserved bacon and chopped parsley, and stir until combined. Transfer the mixture to the prepared pan. Combine together additional Asiago, Cheddars, Mozzarella, and Parmigiano cheeses in a bowl and sprinkle evenly over the top of the macaroni. Bake in the oven until heated through and the top is lightly golden brown (about 12-15 minutes). Remove from the oven and let rest 10 minutes before serving.