Preheat oven to 350°
Prepare a 13x9 pan with baking spray and parchment on the bottom for easy release.
In a large bowl whisk sugar and eggs.
With a spatula stir in flour, milk, pumpkin, butter, oil, baking powder, vanilla, and pumpkin pie spice until smooth.
Pour into pan and bake for 30-35 minutes or until a toothpick comes out clean.
In a bowl with a whisk or mixer whip heavy cream with sugar and dry milk any additional flavor until stiff peaks form.
Spread whipped cream over cake, use the back of a spoon to create peaks and valleys or spread it smooth if you prefer and top with pepitas.