Start by boiling water and cooking the jumbo pasta shells until they are al dente. You will know they are ready when they are tender yet firm to the bite. Undercooking is key; you do not want them to fall apart while stuffing.
Blend ricotta cheese, chopped spinach, and heavy cream in a bowl until it is smooth. Add in lemon juice, dijon mustard, Old Bay seasoning, and Italian seasoning. The filling should smell fresh and aromatic. Remember to taste and adjust seasoning; a bland filling will ruin your stuffed shells.
Gently fold in the claw crab meat and chopped shrimp into the ricotta mixture. This should create a chunky and hearty filling. The seafood needs to be evenly distributed for every bite to be flavorful. Be careful not to overmix; you want to keep those juicy shrimp pieces intact.
In a pot, combine heavy cream, almond milk, sea salt, black pepper, garlic powder, and onion powder. Heat it over medium until it starts to simmer and thicken slightly, filling your kitchen with a creamy aroma. Letting it simmer longer can help thicken the sauce; just avoid burning.
With the shells cooked and the filling ready, carefully scoop the seafood mixture into each pasta shell. Do not overstuff them; leave room for expansion while baking. Stuffing too much will likely cause them to burst in the oven.
In a baking dish, pour a layer of the creamy sauce on the bottom, then place the stuffed shells in a single layer. Cover them with the remaining sauce, letting it soak into the shells. It should look inviting with a nice saucy layer. Skipping this step could lead to dry shells.
Sprinkle shredded mozzarella generously over the top of the shells. It should create a deliciously cheesy layer. This is a great moment to add more toppings like fresh parsley for color. A common mistake is rushing this part — you want a good cheesy crust.
Bake the assembled dish until it is bubbling and golden brown on top. The inviting aroma should fill your home. Keep an eye on it towards the end to prevent burning. Once done, let it cool slightly before serving, so you can enjoy it without burning your mouth.