Heat the olive oil in your large skillet over medium heat. Add the diced onion and bell pepper, cooking until softened and fragrant, about 5 minutes. Stir in the minced garlic and cook for another minute until aromatic.
Add the peeled and deveined shrimp to the skillet. Season with salt, pepper, and half of the Italian seasoning. Cook until the shrimp turn pink and opaque, about 2-3 minutes per side. Remove the shrimp and set aside to prevent overcooking.
In the same skillet, stir in the marinara sauce, remaining Italian seasoning, ricotta cheese, and cream cheese. Let the cheeses melt into the sauce, stirring frequently until smooth and creamy. Slowly add the broken lasagna noodles, stirring to coat them well with the sauce.
Add enough water (about 2 cups) to barely cover the noodles. Bring to a gentle simmer, cover with the lid, and cook for 10-12 minutes, stirring occasionally, until the noodles are tender and have absorbed much of the sauce.
Stir in the fresh spinach until wilted, then return the cooked shrimp to the skillet. Sprinkle the shredded mozzarella and grated Parmesan evenly over the top. Cover and let sit for 2-3 minutes off the heat to allow the cheese to melt.
Give everything a gentle stir and serve hot. This Creamy Shrimp Lasagna Skillet pairs perfectly with a crisp green salad or garlic bread for a complete meal.