Tip: I placed the prep of the ingredients throughout the recipe because it's a time saver. If this overwhelms you, feel free to prep all ingredients before starting.

• Preheat oven to 350 degrees and place oven rack in center position
• Place a large pot of salted water on high heat. Cook pasta shells to package instructions, drain well and rinse with cold water. While you wait for water to boil and pasta to cook, prepare sauce.
• Place pan on medium heat for two minutes. Add olive oil, when it shimmers, add sausage to pan. Cook for 7-8 minutes breaking it up with a spatula. Now it's time to prep your garlic.

  When sausage has cooked for 8 minutes (drain fat if desired), add crushed tomatoes, oregano, red pepper flakes, garlic and a couple of generous pinches of sea salt and freshly ground pepper, to taste. Stir, then let simmer on low heat for 15 minutes.
• While sauce simmers, chop basil, zest lemon with a microplane, and place spinach in a colander and press with a paper towel until excess water is removed. In a bowl mix together ricotta cheese, mozzarella cheese, chopped basil and lemon zest. Stir, add some kosher salt, to taste and stir again. Set aside.
• When sauce has simmered for 15 minutes, turn off heat. Add spinach to sauce and stir well.
• Gently unfold shells and spoon about 1 1/2 tablespoons of ricotta mixture into each shell, place them in the pan on top of sauce. When you have used all the shells, sprinkle them with shaved parmesan, making sure they are covered well with cheese.
• Transfer pan to oven and bake for 35 minutes. Remove from oven, allow to cool for five minutes. Serve. Tip: I usually place a cooking sheet on the oven rack below to catch any sauce drips that happen when sauce simmers.