In a medium bowl, mix together the pumpkin puree, heavy cream, nutmeg and cinnamon. Season with salt and pepper. Set aside.
In another large bowl, mix the ricotta with the eggs, basil, 1 cup of mozzarella, and half a tablespoon of salt and ⅛ teaspoon of pepper. Set aside.
Toss the pumpkin slices with 2 tablespoons of olive oil in a bowl. Set aside.
Preheat the oven to 400°.
In a large pot of boiling salted water, cook the lasagna sheets according to packaging’s instruction. Drain well and transfer the lasagna to a baking sheet.
To assemble, in a 12 inch nonstick skillet, layer 4 lasagna sheets on the bottom, overlapping them slightly. Spread half of the pumpkin mixture over the lasagna in an even layer. Top with half of the ricotta mixture.
Repeat the layering with lasagna sheets, pumpkin, and finish with the ricotta mixture.
Sprinkle the Parmesan and remaining mozzarella over the ricotta layer.
Finish the layers with sliced pumpkin. Brush the pumpkin slices with extra olive oil.
Cover the lasagna with foil and bake for about 25 minutes, until heated through and slightly firm.
Remove the foil and bake for another 35 minutes or the pumpkin slices are caramelized.
Remove from the oven and let stand for 10 minutes.
While the lasagna is cooling down, prepare the fried sage.
In a small skillet, add olive oil over medium heat.
Add sage leaves and cook for 2 minutes until crisp.
Serve the lasagna with fried sage leaves and extra cheese if desired.