Boil a large pot of water and salt until it is at a rolling boil. Add pasta shells and cook for about 2 minutes less than the directions on the package - these will fully cook in the oven.
Once shells are done, drain and set aside. Blanch them with a quick ice bath to completely stop the cooking process.
Heat a large skillet on medium heat and add olive oil.
Add spinach, chopped shrimp, salt, and black pepper to your skillet and sauté for about 5 minutes until shrimp turn pink. The spinach will release water as it cooks down; drain any excess liquid.
In a medium-sized bowl, add shrimp/spinach mix, crab meat, and ricotta cheese. Season with the Italian seasoning, Old Bay, lemon juice, and dijon mustard.
Stuff your shells with the seafood mixture. You can use piping bags or get down and dirty with a regular serving spoon and (washed!) hands.
Preheat oven to 350°F.
Add the heavy cream and almond milk to a shallow saucepan. Season with the salt, garlic powder, onion powder, and fresh parlsey.
Heat for about 8 minutes, stirring occasionally, until the sauce begins to bubble and thicken.
In a 9x13 baking dish, pour the homemade white sauce on the bottom of the pan.
Layer stuffed shells on top of the sauce. Pour any remaining white sauce on top of the shells.
Bake for 15 minutes, covered in aluminum foil. Remove the foil and continue baking for another 5 minutes until the tops begin to brown and the sauce is bubbling.
Sprinkle a bit of parmesan and fresh chopped basil on top of the shells and serve while hot. Enjoy!