Make Treasure Cave Blue Cheese mornay sauce: Melt butter over medium heat, add flour and stir with a wooden spoon for 60 seconds to make a roux. Slowly whisk in milk, then constantly whisk until thickened, around 2-3 minutes. Add Treasure Cave Blue Cheese crumbles and mix until combined. Season with salt and pepper.
Season tomato slices with salt and pepper, then broil for 2-3 minutes.
Assemble hot browns by layering toast with turkey, tomato slices and a generous amount of mornay sauce.