2 tsp olive oil
1/2 cup diced onion, divided
4 large garlic cloves, minced and divided
1/2 cup red wine
6 oz tomato paste
12 oz water
1 tsp sugar
1 3/4 tsp kosher salt, divided
1/2 tsp italian seasoning
1 lb lean ground beef
1/2 cup whole milk ricotta
1/2 cup frozen spinach, thawed and squeeze of any excess moisture.
1 large egg
1/2 cup grated parmesan cheese, plus more for garnish
1 lb large shells
8 oz fresh mozzarella cheese, cut into cubes.
Preheat oven to 375 degrees. Bring a large pot of water to a rolling boil. Season liberally with salt. It should be as salty as the sea.
Heat a large skillet with high sides to a medium-low heat. Add olive oil. Once the oil is hot, add 1/4 cup of the onion and half of the garlic. Saute for 1-2 minutes until slightly softened and fragrant. Season with a little bit of salt and pepper. Add in red wine. Bring the mixture to a boil and then reduce to a simmer. Simmer until reduced by half.
Whisk in tomato paste. Cook for 1 minute. Whisk in water, 1/2 teaspoon salt, sugar, and italian seasoning. Bring to a boil and reduce to a low simmer. Cover and simmer for 10-15 minutes. Season to taste with salt and pepper.
In another medium non-stick skillet. Cook the ground beef until slightly browned and almost all the way cooked through. If any excess grease is produced, drain. Add remaining onion, garlic, and 1 teaspoon salt. Continue to cook until beef is cooked all the way through and onion and garlic are soft, about 3-4 minutes. Remove from heat and cool.
Drop the pasta shells in the water and cook until aldente.(I like to cook them all even though we only use 12 becaue some will bread.) DO NOT OVER COOK. Use a slotted spoon to pull the shells out one by one. Drain of any excess water and let cool.
Once the beef has cooled slightly, add remaining 1/4 teaspoon salt, spinach, ricotta, parmesan cheese, and egg. Mix to combine. Season to taste with salt and pepper. (I added an extra 1/4 teaspoon of salt, but I like things on the saltier side.)
Transfer filling to a large ziplock bag. Cut off about 3/4-inch of the tip. Pipe the filling into the cooled shells. Turn the heat off on the sauce and arrange shells in the pan. (If you’re using store-bought marinara, just pour the marinara into a skillet with high sides and arrange the stuffed shells in the pan.)
Spoon a little bit of the sauce on top of the shells, but don’t completely cover them. Sprinkle shells with mozzarella. Bake until cheese has melted and sauce is bubbly and hot, about 20 minutes. Garnish with extra parmesan cheese.