Preheat oven to 350°
Combine sugar, flour, salt and baking powder in a bowl. Add the vanilla extract and milk and mix together. Set aside.
Pour the melted butter into a 13x9" baking pan. Pour your mixed ingredients into the pan.
In a large bowl, combine and mix eggs, milk, pumpkin. brown sugar, 1 c. granulated sugar, flour and spices, Pour over the top of the crust mixture in the pan. Dot the 2-tbsp. butter and sprinkle 4 tbsp. granulated sugar across the top. The crust will rise to the top as it bakes.
For marshmallow topping, mix together the powdered sugar, ½ and ½, vanilla, and marshmallow fluff till smooth.
Bake the cobbler for approximately 1-hour, until a toothpick inserted into the center comes out clean and the top is browned.
Remove to a wire rack to cool. Scoop into dessert dishes. Drizzle with the marshmallow topping if desired. Sprinkle with pecan halves. Serve with whipped cream.