Step 1

Preheat oven to 425°F and grease a 12x17-inch baking sheet with 1 tablespoon of the olive oil. Set aside.

Step 2

In a medium skillet over medium heat, heat 1 tablespoon olive oil along with the garlic and pepper flakes. Cook until fragrant, stirring often, about 1 minute.

Step 3

Add spinach and salt and cook, again stirring often, until the spinach is mostly wilted, about 1 more minute.

Step 4

Remove spinach to a colander and press out any excess liquid. Remove spinach to a bowl and using kitchen scissors, cut spinach into small pieces. Add ricotta and stir to combine. Set aside.

Step 5

Wipe out skillet and set over medium heat. Add remaining olive oil, then add sausage and brown undisturbed until the first side has browned, about 3 minutes. Using a wooden spoon, break apart the sausage into bite-sized pieces. Continue cooking, stirring frequently and breaking apart the meat as needed, until sausage is cooked through and lightly brown, about 5 minutes more.

Step 6

Add onion to skillet and cook until starting to soften, 3 minutes more. Remove from heat.

Step 7

While sausage cooks, bring a large pot of salted water to a boil over high heat. Cook pasta 1-2 minutes less than package directions indicate, stirring often. Drain and reserve 1/2 cup pasta water.

Step 8

While pasta cooks, add marinara to the sausage mixture. Add pasta water, drained pasta, 1 cup of the mozzarella, and 1/2 cup parmesan, and stir to combine.

Step 9

Spread mixture on prepared baking sheet, then dollop with the ricotta mixture. Sprinkle with remaining mozzarella and parmesan and bake until pasta is tender, sauce is bubbly, and top is lightly browned, about 30 minutes.

Step 10

Let rest 5 minutes before slicing and serving. Enjoy!