To make Enchilada Sauce, heat the oil in a medium saucepan over medium heat. Add the scallions and saute until softened, about 2 minutes. Stir in the flour. Slowly pour in the tomato sauce while stirring. Add the water, paprika, salt, oregano, cumin and black pepper and stir well. Bring to a boil, reduce heat and simmer about 10 minutes, stirring occasionally, until slightly thickened. Remove from heat and set aside.
To make the Enchiladas, preheat oven to 400 degrees F. Spray a shallow baking dish with cooking spray. Combine the pumpkin, 2 tablespoons Enchilada Sauce and 1/4 teaspoon each salt and pepper in a small bowl.
Lay tortillas flat on a clean, dry surface. Spread each tortilla with 1 teaspoon Enchilada Sauce. Place about 2 tablespoons of the pumpkin mixture on each tortilla. Top each with 1 tablespoon shredded cheddar cheese. Roll tortillas up and place seam side down in prepared baking pan. Pour 1/4 cup Enchilada Sauce on top. Bake for 8 minutes. Sprinkle evenly with 1/4 cup shredded cheddar cheese and bake until melted, about 5 minutes more.
Serve with sour cream and more sliced scallions if desired.