Cook ground beef and season to taste. I use garlic salt, onion powder, cumin, chili powder, and black pepper. Or season with taco seasoning mix.
Drain meat and keep warm.
In large skillet or on a flat griddle/grill pan, on medium heat, place two slices of bread, buttered side down.
Sprinkle shredded cheese on both slices.
Cook until buttered side is nicely browned and cheese is melted. You may need to cover the pan to help melt the cheese.
Remove bread from pan and spoon cooked taco meat onto each slice. Fold on the diagonal and top with your favorite taco toppings.