Preheat oven to 450 to cook the spaghetti squash.
Cut the spaghetti squash into thirds crosswise through the middle.
Remove the seeds by using a knife or spoon.
Place squash rounds on a greased baking sheet and sprinkle with salt.
Place baking sheet in the oven on the middle rack and roast for 30-40 minutes.
Let cool.
While squash cools, cook the turkey in saute pan over medium-high heat until browned and cooked through.
Add marinara to pan and mix.
When squash cools enough to handle it, use a fork to remove strands from the rind.
Transfer them to the greased casserole dish, spreading to cover the bottom.
Sprinkle with half the garlic salt.
Top with meat sauce.
Drop spoonfuls over ricotta over the dish, and alternate with rounds of mozzarella.
Sprinkle with the other half of the garlic salt.
Preheat oven to broil.
Place casserole under the broiler for 5-10 minutes until cheese begins to brown.
Remove casserole from oven and tuck baby spinach leaves into the casserole.
Return casserole to broiler for one more minute until spinach softens.
Remove casserole from oven and let cool for 15 minutes.
