Make sure to deseed the butternut squash when chopping it. You will be blending it so size doesn’t matter too much. However make them uniform to help even cooking.
Brush with oil or broth and bake on a parchment lined baking sheet for 35 minutes, or until soft but not too brown. When done remove from oven and allow to cool.
While butternut squash is baking, soak sundried tomatoes in some warm water to soften them a bit.
Cook shallots, sage, rosemary and garlic in a pan over medium heat with drizzle of oil or broth until soft. About 2-3 minutes.
Add mushrooms and salt and cook until most of the released liquid evaporates, about 5 minutes, then mix in spinach.
Remove from heat and set aside to cool.
Put all ingredients for the ricotta into the food processor or blender. Pulse until you achieve a chunky ricotta like consistency. You do not want this silky smooth. Use a blender for less clean up but be aware that the mixture won't move around as well in a blender and it will be harder to get the right consistency. You will need to stop and mix more often that if you're using a food processor.
Add the ricotta to the veggie mixture and mix until combined. Set aside.
Once butternut squash is cooled, add it to a blender along with the rest of the ingredients. Blend until you achieve a silky smooth consistency.
Cook lasagna noodles. Make sure to only cook them half the time than the directions say on the box since you will be baking them, this will avoid mushy noodles. To prevent sticking, leave them in some cool water.
Pour about 2 cups butternut squash sauce on the bottom of a 9x12 baking dish. Enough to coat it well.
To make lasagna roll ups:
Lay a lasagna noodle flat on your workspace
Spread a few spoonfuls of the ricotta/veggie mix over the top of it
Starting at one end, roll it up
Place in the baking dish
Repeat with all lasagna noodles
Once all lasagna noodles are rolled up pour the rest of the creamy butternut squash sauce over the roll ups. Sprinkle with parmesan if using. Top with the basil if using.
Bake covered with foil for 15 minutes.
Remove the foil and bake another 15 minutes.
Allow to cool a bit and enjoy!
If you are not using a high speed blender, you can soak the cashews overnight, boil them for 30 minutes or grind the dry cashews into a fine powder using a coffee grinder (do not boil them for this method). For the ricotta, it's best to soak or boil to get the right texture.
You can also adjust the seasonings for this and use thyme or other flavors you prefer.