Bake waffle fries to package directions. Heat butter in a small pot over medium heat and whisk in flour. Cook the flour a minute then add the tomato paste. Cook paste a minute then whisk in milk. When sauce bubbles, stir the cheese and chipotles into it. Season the sauce with salt, to taste.
Remove fries from oven when crisp and golden brown. Spoon the thick cheese sauce over waffle fries and serve.