Roast the Butternut Squash:

1. Peel the butternut squash and slice into 1/4-inch pieces. In a large mixing bowl, add the butternut squash, oil, salt, and pepper. Toss well to coat.
2. Place the squash slices into a large parchment-lined half sheet baking pan and bake in a 375F preheated oven for 35- 40 minutes until fork tender and golden brown. Set aside.

Cook Lasagna Noodles:

1. While baking the butternut squash, prepare the noodles by bringing a large pot of salted water to a boil over medium-high heat. Add lasagna noodles and oil and cook until al dente (fully cooked but still firm) according to package directions, about 8-10 minutes.
2. Rinse the noodles under cold water to cool off completely and set aside in the pot.

Make the Creamy Spinach Sauce:

1. In a large shallow saucepan or 4 qt. Dutch oven, melt butter over medium-high heat until it starts to bubble, about 1 minute. Add onion and garlic and sauté until tender, about 3-4 minutes.
2. Stir in flour. Mix well and cook for 1 minute. Pour in half and half cream, stirring well and bring to a boil, about 6-8 minutes.
3. Add cheese and season with salt and pepper. Lower heat to medium and let the mixture simmer for 5-7 minutes until thickened to a desired consistency, stirring occasionally. The sauce should be similar to a gravy consistency and thick enough to coat the back of a spoon. Turn off the heat and stir in spinach evenly until wilted, about 1 minute. Set the sauce aside.

Make the Ricotta Cheese Mixture:

1. In a medium mixing bowl, stir together mozzarella, ricotta, Parmesan, parsley, and egg until evenly combined. Set aside.

Assemble the Lasagna:

1. Sauce. Add and evenly spread 1 cup of creamy spinach sauce on the bottom of a 9x13-inch casserole pan.
2. Noodles. Place 3 lasagna noodles evenly apart over the sauce.
3. Cheese. Spread 1/2 of the cheese mixture over the noodles.
4. Butternut Squash. Place 1/2 of the roasted butternut squash slices over the cheese.
5. Sauce. Spread 1/2 of the remaining sauce evenly over the squash slices.
6. Noodles. Place 3 lasagna noodles evenly apart over the sauce.
7. Cheese. Spread remaining 1/2 of the cheese mixture over the noodles.
8. Butternut Squash. Place remaining 1/2 of the roasted butternut squash slices over the cheese.
9. Noodles. Place 3 lasagna noodles evenly apart on top.
10. Sauce. Spread remaining sauce evenly over the squash slices.
11. Mozzarella. Top with the remaining mozzarella. 

Bake the Lasagna:

1. Lightly grease a large piece of aluminum foil and cover the pan. Greasing the foil prevents the melted cheese from sticking to the foil while baking.
2. Bake the lasagna covered in a preheated 375 F oven for 45 minutes. Remove the foil and bake uncovered for another 15-20 minutes or until the melted cheese turns golden brown and bubbly. Optionally, turn on broiler on high and broil for 3-4 minutes to get the crispy and brown cheesy crust.
3. Let the lasagna rest for at least 15 minutes before slicing. This is to ensure the cream sauce sets a bit and is not too runny.