Preheat oven to 350 degrees.
Cook the bacon in a pan over medium heat, until crispy. Drain any excess bacon fat.
Add the ground beef. Cook for several minutes, stirring frequently, until fully cooked.
Add three slices of the American cheese. Stir until melted. Taste and season with salt and pepper, to taste. Set aside.
To prepare the sauce, melt butter in a pan over medium heat. Add the flour. Stir to combine. Cook for 1-2 minutes, stirring constantly.
Gradually whisk in the milk. Bring the mixture to a simmer and continue whisking until the mixture begins to thicken.
Turn down the heat. Add the cheddar cheese and two remaining slices of American cheese. Stir until melted.
Stir in the chopped tomato. Season with salt and pepper, to taste.
To assemble, spray a baking dish with non-stick cooking spray.
Place a generous spoonful of the meat filling into the center of each tortilla. Roll the tortilla around the filling and place seam-side down in the baking dish.
Repeat until each tortilla has been filled, placing the enchiladas side by side in the baking dish.
Pour the cheese sauce over the enchiladas. Sprinkle with additional shredded cheddar cheese.
Bake for about 30 minutes.
Garnish with additional crumbled bacon and ketchup, if desired.
