Preheat the oven to 375°F.

Cook the jumbo pasta shells in a large pot of salted boiling water according to package directions until just al dente. Drain and spread on a baking sheet or tray to cool slightly.

Heat a large skillet over medium heat. Add the ground beef and diced onion. Cook, breaking up the beef, until browned and the onion is softened. Drain any excess grease.

Add the minced garlic and cook for 30 seconds until fragrant.

Stir in the taco seasoning and water. Simmer for 2 to 3 minutes until the liquid is absorbed and the mixture is well combined. Remove from heat.

In a large mixing bowl, combine the taco meat mixture, ricotta cheese, 1 1/2 cups of the shredded cheese, and cilantro if using. Stir until evenly mixed.

Spread 1 cup of taco sauce over the bottom of a 9x13-inch baking dish.

Fill each pasta shell with the taco mixture and arrange them in the baking dish. Pour the remaining 1 cup of taco sauce over the top. Sprinkle with the remaining 1/2 cup of shredded cheese.

Cover the dish tightly with aluminum foil and bake for 20 minutes.

Remove the foil and bake for an additional 10 minutes until the cheese is melted and bubbly.

Serve warm with sour cream, sliced green onions, or your favorite taco toppings.