Pulse the onion, carrot, and celery in a food processor until finely chopped. Heat olive oil in a dutch oven or large pot over medium heat. Add mirepoix and tomatoes, cook, breaking up the tomatoes with a spoon, until moisture is evaporated. Add wine to the dutch oven and bring to a boil, stirring about 2 minutes. Add salt, red pepper flakes, and vegetable broth; bring to a boil, reduce heat, and simmer 30 minutes. Let the sauce cool. Stir in fresh herbs.
Slice pumpkin in half, discard seeds and save for another use; brush with oil and season with salt and pepper. Place flesh side down on a large baking sheet, add a thin layer of water to the baking sheet and roast 35-40 minutes. Cool pumpkin, scoop out flesh and puree in a food processor until smooth adding 1 tablespoon of water at a time as necessary. Transfer puree to a medium mixing bowl; add brown sugar, cinnamon and nutmeg, stirring to combine.
Combine ricotta, mozzarella, whisked egg, fresh herbs, salt and pepper in a medium bowl. Stir to blend, adding fresh pasta water 1 tablespoon at a time to soften.
Assembling the Lasagna
Preheat oven to 350 degrees. Lightly coat a 13x9" baking dish with a drizzle of olive oil. Spread 1/4 cup tomato sauce in the prepared baking dish. Top with a layer of noodles, spread over 3/4 cup tomato sauce, 1/2 of the cheese mixture, and top with 1 1/2 cups pumpkin. Repeat the process, starting with noodles and ending with pumpkin, for a total of 2 layers. Top with one more layer of noodles, 1/2 cup sauce and a generous layer of Parmesan cheese. Place baking dish on a rimmed baking sheet and bake lasagna until bubbling and beginning to brown on top, 50 minutes. Let lasagna sit 25 minutes before serving. Garnish with chopped garden herbs.
Lasagna can be assembled 12 hours ahead. Cover and chill. Let sit at room temperature 1 hour before baking. Cook, covered with foil until the last 20 minutes, then finish cooking uncovered.