1.75 pounds (29-ounce can) cooked sweet potatoes 1/4 cup brown or brown sugar, packed 2 tablespoons maple syrup 3 tablespoons unsalted butter , softened 1 teaspoon salt 1 teaspoon ground cinnamon 1/2 teaspoon vanilla extract 1/2 cup finely chopped pecans , divided in half non-stick cooking spray 1 cup vegan mini marsh