Spray a square baking dish with cooking spray, and fill dish with cubed bread and ham. Lightly mix them together with your fingers.
Heat a 10″ skillet over medium heat, and add Country Crock spread. As soon as it melts (will happen quickly), add flour and whisk together until well combined.
Slowly stir in milk, whisking constantly, and continue cooking over medium heat until bubbly and thickened, about 8 minutes. Use your whisk to break up any clumps of flour that might form. Reduce heat to low, add 1 c. cheese, and stir until melted.
Pour sauce evenly over bread and ham. Cover with foil, and bake 15 minutes.
Remove foil, arrange tomato slices over the top of the casserole, sprinkle black pepper on tomatoes if desired, and spread remaining 1/2 c. cheese over the top. Bake an additional 15 minutes. Serve and enjoy!