Cook the pasta per the manufacturer's instructions. Drain well and spread out onto a baking sheet to cool and dry.
Meanwhile, crumble the sausage (remove from casings first if using links) into a large skillet and cook over medium-high heat until almost done.
Add the onion and continue cooking until it has softened and the sausage is cooked through.
Add the spinach. Stir and cook another 2-3 minutes or until wilted.
Remove skillet from heat and let cool for 5 minutes.
Stir in 1 cup of the mozzarella and 1/2 cup of the Parmesan along with the egg, garlic powder, salt and pepper. Mix well.
Spray the two pans with non-stick spray.
Fire up your Big Easy so it heats up while you stuff the pasta tubes.
Spread 1/4 cup of the spaghetti sauce in the bottom of each pan.
Stuff each manicotti with the sausage mixture. I prefer to block one end of the tub with one hand while using the other hand to stuff the tubes (gently).
Place stuffed tubes into the pans. Do not stack. You might have to kind of wiggle and shove them in to get them to fit.
If you have leftover meat mixture just sprinkle it around and in between the manicotti.
Divide remaining sauce over the tops of the manicotti.
Cover the fans with foil.
Place one pan in the bottom of your Big Easy. If you have 2 Bunk Bed baskets, put the pan in a basket instead and lower it to the bottom of the Big Easy basket and attach at the sides.
Place the other pan in a Bunk Bed basket and lower it into the Big Easy basket. It will rest on top of the first basket if you are using two. Otherwise, just attach it to the sides of the Big Easy basket just above the first pan.
Cook for 35 minutes. There is no need to swap the pans.
Remove the foil. Top the pans with the remaining cheeses.
Return the pans to the Big Easy and cook another 20-25 minutes or until the cheese is melted and turns golden brown. The top pan will cook slower than the bottom. If desired, rotate the pans after 15 minutes.
Remove pans from the Big Easy and let rest 15 minutes.
Garnish with parsley and serve.