Preheat oven to 350°F.
In a skillet over medium heat, brown the ground beef until fully cooked with no pink remaining. Drain excess fat.
Stir in taco seasoning and the full undrained can of diced tomatoes and green chiles. Mix well and simmer for 5 minutes. Remove from heat and let cool slightly.
In a large bowl, combine shredded cheddar cheese and ranch dressing. Add the cooked taco meat and stir until everything is well mixed.
Spoon the taco mixture into frozen phyllo tart shells, about one heaping spoonful per shell. (To freeze for later: place filled shells on a baking sheet, freeze until solid, then transfer to a zip-top freezer bag.)
Place filled shells on a baking sheet and bake for 8–10 minutes until cheese is melted and shells are golden and crispy. If baking from frozen, bake for 10–13 minutes.
Serve immediately with optional toppings. Enjoy!