In a large skillet, cook beef over medium heat until no longer pink, 5-7 minutes, breaking into crumbles; drain. Stir in taco seasoning and water. Bring to a boil. Reduce heat; simmer, uncovered, until thickened, 2-3 minutes.

Meanwhile, sprinkle 1/4 cup cheese over 1 side of each tortilla. Place on a microwave-safe plate; heat, uncovered, on high for 15-20 seconds or until cheese is melted. Immediately wrap each tortilla around a taco shell. Fill with beef mixture. Drizzle with spicy ranch dressing. Serve with toppings of your choice.