In a large skillet, heat the oil on medium-high. Add the mushrooms, onion, and garlic. Cook 8 min., until mushrooms begin to soften, stirring occasionally.
Drain the tuna. Stir tuna, cream of mushroom soup, and milk into the skillet, breaking up tuna with the back of a spoon. Cook 2 min. Stir in the green squash noodles. Cook 1 min., until soup is hot and bubbling. Remove from heat. Crush the Parmesan crisps and sprinkle over the mixture in the skillet. Serve immediately.