Reduce the heat to medium/low and bring the sauce to a simmer until the heavy whipping cream has reduced and thickened. Keep whisking until it does not stick to the bottom of the pan. It will take a few minutes for the sauce to reduce and thicken. Once thick, add the Parmesan cheese and Pepper Jack cheese and continue to stir until the cheese melts and the sauce is smooth. Pour the cheese sauce over the asparagus in the middle of the casserole, avoiding the tops of the asparagus. Next, sprinkle mozzarella cheese and crushed red pepper flakes over the cheese sauce.
Bake for 15 minutes. If you prefer crunchy asparagus, you can reduce the baking time by 2–3 minutes. Remove from the oven and add bacon crumbs to the top. Bake for another 3 minutes and Enjoy!
