More ground black pepper and dried rosemary for garnish (optional)
Place all the ingredients except the lasagna noodles and sweet potatoes in a food processor and blend until it''s smooth and silky
In a greased, rectangular baking dish, spread a couple of ladlefuls of the pumpkin sauce. Then layer on four lasagna noodles, slightly overlapping.
Spread a third of the remaining pumpkin sauce and add a layer of sweet potatoes on top.
Place another layer of lasagna noodles and repeat.
On the third and final layer of lasagna noodles, layer the sweet potato slice and then pour over and spread the remaining pumpkin sauce.
Sprinkle some pepper and dried rosemary on top, cover with foil, and bake in a 350-degree preheated oven for 45 minutes.
Remove the foil and let the lasagna bake another 15 minutes until the top is slightly golden-brown.
Remove from the oven and allow it to cool slightly before serving.