01 - Preheat oven to 375°F. Grease a 9-inch pie dish or deep baking dish with nonstick spray or butter.
02 - Bring a large pot of salted water to a rolling boil. Cook spaghetti until just al dente, then drain thoroughly and set aside.
03 - While the pasta cooks, heat a large skillet over medium heat. Add the ground Italian sausage, breaking it apart with a wooden spoon, and cook until evenly browned. Drain off any excess fat.
04 - Add the diced onion, chopped bell pepper, minced garlic, and diced jalapeños to the skillet with the sausage. Sauté for 4 to 5 minutes until the vegetables are softened and fragrant.
05 - Stir in the marinara sauce, tomato paste, crushed red pepper flakes, dried oregano, and smoked paprika. Season with salt and black pepper to taste. Let the sauce simmer gently for 5 minutes to meld the flavors.
06 - In a large mixing bowl, combine the drained spaghetti, ricotta cheese, beaten eggs, and chopped fresh basil. Toss until the pasta is evenly coated throughout.
07 - Transfer the spaghetti mixture into the prepared pie dish, pressing it evenly across the bottom and up the sides to form a crust layer.
08 - Spoon the sausage and vegetable sauce evenly over the spaghetti crust. Sprinkle the shredded mozzarella and grated Parmesan uniformly over the top.
09 - Bake for 25 to 30 minutes until the cheese is fully melted and golden brown on top. Remove from the oven and let rest for 10 minutes before slicing.
10 - Scatter additional fresh basil leaves over the top. Slice into wedges and serve warm.