First, begin with cutting the butternut squash into cubes in order to cook, you can either boil in water for up to 20 minutes or until tender and you can also bake them in the oven for about 15 minutes or as needed.
Once the butternut is cooked, transfer to a food processor and puree then add the ricotta cheese, milk, salt and nutmeg and pulse to combine.
You can add more milk as per your liking, which will also make the filling creamier.
Adjust salt & nutmeg as needed.
For the Spinach filling
Heat 1 Tbsp. of olive oil to a skillet, add the frozen spinach and allow thawing. Once the spinach begins cooking, add the minced garlic and cook until fragrant. Add salt and pepper to taste and mix over low heat for another 4-5 minutes.
Once the spinach is well cooked, allow cooking for a few minutes then add the ricotta cheese followed by the mozzarella cheese mixing all together.
Adjust salt and pepper to taste.
For the Lasagna Sheets
Bring a wide pot of water to boil, and place the lasagna sheets one by one in the boiled water to cook as per the package instructions.
I usually dip each sheet for a few minutes and remove, when I am ready to assemble the lasagna altogether.
How to assemble
Begin by greasing your lasagna dish with a tsp. of olive oil to prevent the bottom from sticking when you are ready to cook.
Spread 1/3 of the butternut squash filling on the bottom, sprinkle with some mozzarella cheese and top with cooked lasagna sheets
Spread half the spinach filling over the lasagna sheets, top with mozzarella cheese, and top with another layer of cooked lasagna sheets
Spread another layer of butternut squash filling, sprinkle with mozzarella cheese and top with cooked lasagna sheets.
Spread with another layer of spinach filling, top with mozzarella cheese and a final layer of lasagna sheets.
Spread the remaining amount of butternut squash filling over the last layer of lasagna sheets, sprinkle with mozzarella cheese and finally grated parmesan cheese.
Sprinkle the Italian seasoning, dried basil and paprika on top.
Cover with foil and bake for 30 minutes.
Remove the foil and bake for a final 10 minutes until the top is golden brown.