Heat a small pot over medium heat. Add butter and melt. Add flour to butter and cook 1 minute. Whisk in milk and season sauce with salt and chipotle powder or smoked paprika. Stir in cheese and melt. Thicken sauce 1 minute. Stir in salsa and remove from heat. Serve sauce from hot pot and return to stove, as necessary, to loosen.
Cut carrots in half then stand on end and cut thin strips. Cut strips across on an angle, forming 2 long triangles. Lightly salt the carrots. Pile chips into a bowl and tuck carrots in and around the chips. The blue and orange triangles are your "witches hats".