Preheat oven to 400 degrees F. Coat bottom and sides of a 13 by 9-inch baking dish with butter.
Arrange the bacon on an aluminum foil lined sheet pan and bake until crisp, about 22 minutes. Allow to cool and coarsely chop.
Put the chicken and beer in a large bowl and let marinate, at room temperature, for 20 minutes.
Bring a large pot of salted water to a boil over medium heat. Add the macaroni and cook stirring occasionally, until cooked al dente, about 6 to 7 minutes. Drain and reserve in a large pot or mixing bowl.
Melt 1/2 cup butter in a large saucepan over medium heat; whisk in the garlic and cook for 1 to 2 minutes or until golden. Whisk in 1/3 cup flour and cook until golden, about 1 minute. Whisk in 3 cups milk, the salt and the pepper, and bring the mixture to a boil, stirring frequently. Add 2 cups of the Cheddar and 2 cups of the mozzarella (reserving additional cheese for topping) and stir until melted, about 2 minutes.
Stir the cheese sauce, blue cheese and bacon into the macaroni until well combined; pour evenly into the prepared baking dish and smooth the surface.
Put the remaining 1 cup of flour in a medium-sized shallow mixing bowl. In another medium-sized shallow mixing bowl, add the remaining 2 tablespoons milk and the egg and whisk until combined. Drain the beer from the chicken tenderloins and dip into the flour to coat well, then dip into the egg mixture and back into the flour. Put on a plate until ready to fry.
Heat the oil in a large skillet over medium-high heat until hot. Working in 2 batches, fry the chicken until golden brown and cooked through, about 4 minutes per side. Remove to paper towels to drain. Add the chicken and hot sauce to a large bowl and toss until well coated. Carefully slice the chicken into bite-sized strips. (Avoid knocking off the batter).
Evenly top the macaroni with the sliced chicken, and drizzle with additional hot sauce, if desired. Sprinkle remaining 1 cup of white Cheddar and the remaining 1 cup of mozzarella cheese over the top of the chicken and sprinkle with the panko bread crumbs. Melt the remaining 2 tablespoons butter and drizzle it evenly over the bread crumbs. Bake at 400 degrees F until golden brown and bubbly, about 25 to 30 minutes.
Cool 10 minutes before serving. Serve with celery and carrot sticks, if desired.
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