Coat a broiler pan with cooking spray, or lightly apply a thin coat of oil.
Place roast on pan, cover loosely with aluminum foil (to prevent crumb coating from browning too quickly), and bake at 325 degrees for 1-1 1/2 hours or until done to your liking.
Check internal temperature with a meat thermometer inserted in the thickest portion of rost; continue baking until temperature reaches your desired temperature for doneness (140 degree minimum, 160 degrees for medium, 170 degrees for well-done).
Remove from oven, remove foil, and let sit 10 minutes before slicing.
Meanwhile, while roast is cooking, prepare sauce: put flour in a saucepan; gradually add evaporated milk and chicken broth, stirring with a whisk to blend.
Add mustard, maple syrup, salt, and black pepper, and mix well.
Place over medium heat and cook until thick and bubbly, stirring constantly, about 10 minutes.