pre heat oven to 350°f
Shred cheese and mix together setting 1 cup worth aside for assembly. Have all seasonings on hand as you will need to keep a close eye on the sauce once you have started.
In a large saucepan melt butter with flour and stir continuously until flour begins to darken. add evaporated milk and milk and stir constantly until you see that the mixture begins to thicken. moving the spoon through the milk you should start to see waves forming.
add bacon bits, onion flakes salt, pepper, and mustard mix in completely.
add in cheese and stir just until cheese has melted, add remaining seasonings, stir to incorporate, and take off the heat.
add cooked noodles to the cheese sauce and stir until every noodle is drenched in delicious cheese sauce.
prepare a 9x13 baking with cooking spray
pour half of the noodle mixture to layer the bottom of the pan, layer remaining cheese on that and add the rest of the noodles on top.
combine all ingredients for topping and sprinkle on top. bake in the oven for 30 min or until the top is golden brown and the sauce is nice and bubbly.