- 6 tablespoons unsalted butter, divided
- 1 medium onion, chopped
- 2 garlic cloves, finely chopped
- 2 teaspoons kosher salt, divided, plus more
- 3/4 teaspoon freshly ground pepper, divided
- 1 (28-ounce) can whole peeled tomatoes
- 1 (14-ounce) can whole peeled or diced tomatoes
- 1 1/4 cups (packed) basil leaves, coarsely chopped, divided
- 8 ounces dried manicotti noodles
- Olive or vegetable oil (for greasing)
- 1/4 cup all-purpose flour
- 2 cups whole milk
- 1 cup grated Parmesan (about 3 ounces), divided
- 2/3 cup grated Pecorino Romano (about 2 ounces), divided
- 1 pound fresh ricotta
- 8 ounces fresh mozzarella, cut into 1/2" pieces
- 1 shallot, finely chopped
- 1 large egg
- Preheat oven to 400°F. Melt 2 Tbsp. butter in a large skillet over medium heat. Cook onion and garlic, stirring often, until softened, about 3 minutes. Season with 1 tsp. salt and 1/2 tsp. pepper. Add both cans of tomatoes, breaking up with a wooden spoon, then increase heat to medium-high. Add 1/2 cup basil, bring to a simmer, and cook, stirring occasionally, until slightly reduced, 15–20 minutes.
- Cook noodles in a large pot of boiling salted water, stirring occasionally, until al dente. Drain and transfer to a lightly oiled rimmed baking sheet.
- Meanwhile, melt remaining 4 Tbsp. butter in a medium saucepan over medium-low heat. Add flour and cook, stirring constantly, until foamy and nutty smelling, 1–2 minutes. Whisking constantly, gradually add milk and bring to a simmer. Cook, whisking often, until mixture coats the back of a spoon, about 3 minutes. Stir in 1/3 cup Parmesan and 1/3 cup Pecorino; season with 1/2 tsp. salt and remaining 1/4 tsp. pepper.
- Mix ricotta, mozzarella, shallot, egg, 1/3 cup Parmesan, 1/2 cup basil, and remaining 1/3 cup Pecorino and 1/2 tsp. salt in a medium bowl.
- Spoon ricotta mixture into manicotti noodles at both ends. Spread half of tomato sauce then half of cheese sauce (keep them separate but they'll meld together) on bottom of a 13x9" or other 3-qt. baking dish. Arrange manicotti over, then top with remaining tomato sauce, cheese sauce, and 1/3 cup Parmesan. Bake manicotti until bubbling and lightly browned on top, 30–35 minutes. Let cool 5 minutes. Top with remaining 1/4 cup basil and serve.