In a large 10” skillet, add the butter over medium-low heat and melt.
Add the butternut squash and cook low and slow, stirring occasionally until golden brown. (It will seem like too much butter at first, but the squash will soak it up. Once the squash is fully cooked, it will start to caramelize around the edges).
When the squash is done, quickly add the sage leaves to the pan and saute briefly to release the aroma.
Add the squash, sage leaves, salt, pepper, and ricotta to the bowl of a food processor, and puree until chunky and coarsely chopped, some pieces of squash remaining are fine.
Scrape the mixture into a bowl, and have ready.
Spray a 9×5” bread loaf pan with cooking spray. Add half of the heavy cream to the bottom of the pan and tilt to evenly cover the bottom of the pan.
Add one lasagna sheet and break up another sheet to fill any gaps.
Add half of the pureed lasagna mixture on top of the noodle, followed by one-third of the cheese. Repeat. Finish with one final lasagna noodle, drizzled with the remaining half of the cream and cheese.
Order of layers: noodle with cream, butternut squash, cheese, noodle, butternut squash, cheese, noodle with cream, cheese.
Should be covered in foil before baking at 350º for 28-30 minutes.