Step 1

Preheat the oven to 350 degrees F.

Step 2

Coat a 9x13-inch baking dish with nonstick spray.

Step 3

In a large pot of salted, boiling water, cook the pasta shells to al dente according to the package directions.

Step 4

Drain the pasta shells and place them upside down on a baking sheet to dry.

Step 5

In a large skillet over medium heat, cook the ground chuck, while crumbling, until it is no longer pink. Drain the excess fat.

Step 6

Reduce the heat to medium-low, add the oil and the onion to the meat, and cook until the onion is translucent, about 30 seconds.

Step 7

Add the garlic to the meat mixture and cook until it is fragrant, about 30 seconds.

Step 8

Reduce the heat to low, add the marinara sauce to the meat mixture, and simmer, uncovered, while stirring occasionally, for 30 minutes.

Step 9

In a medium bowl, mix the egg, the cottage cheese, 1 cup of the mozzarella cheese, and 1/2 cup of the parmesan cheese together.

Step 10

Pour 3/4 of the meat sauce in the bottom of the prepared baking dish.

Step 11

Stuff the cooked shells with 1 rounded tablespoon of the cheese mixture and arrange them on top of the meat sauce, open-side up.

Step 12

Spoon the remaining meat sauce in between the shells but not directly on top of them.

Step 13

Cover the dish with aluminum foil and bake for 30 minutes.

Step 14

Carefully discard the foil, sprinkle the shells with the remaining mozzarella cheese and the remaining parmesan cheese, and bake until the cheese has melted, about 5-7 minutes.

Step 15

Garnish the shells with the basil and serve.