Step 1

Preheat oven to 350F.

Step 2

Cook shells in a large pot of salted water for 2-3 minutes shy of package directions (just under al dente). Drain, rinse with cold water, and set aside.

Step 3

While the pasta is cooking, heat a large skillet over medium heat. Add the olive oil, then saute the onion along with ¼ teaspoon of salt until translucent, about 3-5 minutes. Add the garlic and cook until fragrant, about 1 minute, stirring frequently.

Step 4

Add the ground beef and ¼ teaspoon salt. Saute until browned and cooked through, breaking into small pieces, about 5-7 minutes. Drain any excess oil, if desired.

Step 5

Add the marinara sauce, stir to combine, then remove from heat.

Step 6

In a large bowl mix together ricotta, egg, spinach, 1 cup Italian cheese blend, ¼ cup parmesan, and ¼ teaspoon salt, stirring to combine.

Step 7

Once the shells are cooked and cooled, fill each shell (about 2 heaping tablespoons) with the ricotta-spinach mixture.

Step 8

Add half the beef marinara sauce to the bottom of a large baking dish, spreading to cover.

Step 9

Arrange the shells in the baking dish, then top with remaining beef marinara sauce and remaining 1 cup mozzarella and ¼ cup parmesan.

Step 10

Cover with foil and bake for 40 minutes, then uncover and bake an additional 5 minutes.

Step 11

Sprinkle with parsley, if using, and serve.