Add flour and stir into a paste. Cook for 3-4 minutes to cook flour. Stirring constantly.
Add the heated milk all at once. Stir briskly to remove any clumps. If required, break up any clumps by pushing it between the side of the pot with your spoon. Stir until partially thickened.
Add cheese. Stir until melted.
Add white pepper. Taste to adjust salt. Don't salt it until the cheese is added. Different cheeses have dfferent levels of salt. Set aside.
Meanwhile, steam cauliflower until slightly softened. Don't cook until totally done, or cauliflower will end up soggy after baking.
Add cauliflower to casserole dish. Cover with cheese sauce. Sprinkle bread crumbs on top.
Bake at 325°F for 30-40 minutes, until bubbly and slightly browned.
Notes
NOTES**
Do not add salt until after cheese has melted. Different cheeses have different salt content.
Do not overcook cauliflower.
Always pre-warm milk.
Mix different cheeses for other flavor profiles.
Use the majority of mild cheese (2/3) and then add lesser quantity (1/3) of sharp cheeses for flavor