It’s a good idea to have everything measured out before you start.
First, cook the macaroni to slightly less than al dente. (The macaroni should still be quite firm. It will continue to cook as it absorbs the sauce and bakes in the oven.)
While it’s cooking, mix all the ingredients for the topping, making sure the butter coats all the Corn Flakes, and set aside.
Strain the macaroni and pour directly into the 9x13 pan. Sprinkle the macaroni with the bacon bits.
In the same pot that you used for the macaroni, melt the butter and quickly whisk in the flour and spices to absorb all the butter.
Add the milk, whisking constantly until the flour mixture is incorporated.
Bring to a boil, still whisking constantly, then turn off the heat.
Add the cheeses and whisk until melted and combined.
Pour the sauce over the macaroni and bacon and stir to coat all the macaroni.
Sprinkle with cheese, then add the Corn Flake topping and spread it out evenly.
At this point, you can either bake it right away, or put it in the fridge for later. I don’t recommend freezing this or making it more than a day ahead of time, because it tends to lose its creaminess, the longer it sits in the fridge. When ready to bake, pre-heat the oven to 350ºF and bake for one hour.