Preheat the oven to 375 degrees. Bring a pot of boiling water to a boil. Add the squash and season with 1 teaspoon of salt. Cook until the squash is tender, about 7 minutes. Remove from the heat and drain. In a large saute pan, over medium heat, melt the butter. Add the squash, sugar, cinnamon and nutmeg. Season with salt and pepper. Saute for 2 minutes and remove from the heat. Keep the squash warm. Season the chicken legs all over with a drizzle of olive oil and salt and pepper. In a small mixing bowl, toss the lemon zest, garlic and onions with olive oil, salt and pepper. Stuff the cavity of each chicken leg with the lemon and onion mixture. Divide the truffle slices into 1/4 and stuff the truffle slices underneath the skin of each chicken leg. Brush the 1/2-circles of dough with some of the beaten egg and place one leg on each piece with the joint sticking out. Fold the ends over to create a wrapper and place, seam side down, on a parchment lined baking sheet. Brush the outside of each package with more of the beaten egg and bake until the crust is brown and the chicken tender, about 35 minutes. Serve the candied squash with the chicken legs.