Chicken Mushroom and Spinach Lasagna

Ingredients:
For the Filling:
2 tablespoons olive oil
1 pound chicken breast or thighs, diced
1 medium onion, finely chopped
3 cloves garlic, minced
8 ounces mushrooms, sliced
3 cups fresh spinach (or 1 cup frozen spinach, thawed and drained)
1 teaspoon dried thyme
1/2 teaspoon dried basil
Salt and pepper to taste
For the Ricotta Mixture:
1 1/2 cups ricotta cheese
1 cup shredded mozzarella cheese
1/2 cup grated Parmesan cheese
1 egg
1/4 cup chopped fresh parsley (optional)
For the Sauce:
2 cups marinara sauce (store-bought or homemade)
1 cup shredded mozzarella cheese (for topping)
1/2 cup grated Parmesan cheese (for topping)
For Assembly:
9-12 lasagna noodles (depending on the size of your baking dish)
Fresh basil or parsley for garnish (optional)