Preheat the oven to 350°F (175°C). Generously grease and flour a 10- or 12-cup Bundt pan, ensuring all crevices are coated to prevent sticking. Set aside.

In a large bowl, sift together the flour, cornstarch, ginger, cinnamon, baking soda, baking powder, allspice, cloves, salt, and nutmeg. Set aside.

In a separate large bowl, use an electric mixer on medium speed to beat the melted butter, vegetable oil, and dark brown sugar until well combined, about 3–4 minutes. Add the molasses and continue mixing until smooth.

Reduce the mixer speed to low. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

Gradually add the flour mixture and buttermilk to the wet mixture in alternating additions, beginning and ending with the flour. Mix on low speed until just combined.

Pour the batter evenly into the prepared Bundt pan and smooth the surface. Gently tap the pan on the counter to remove any air bubbles. Bake for 45–60 minutes, or until a toothpick inserted into the center comes out with only a few moist crumbs attached.

Allow the cake to cool in the pan for 10 minutes. Carefully invert onto a wire rack and cool completely before glazing.

In a small bowl, whisk the powdered sugar, maple syrup, and 1 tablespoon of milk until smooth. Add additional milk as needed to achieve a thick yet pourable consistency.

Once the cake has fully cooled, drizzle the glaze evenly over the cake, allowing it to run down the sides. Garnish with crystallized ginger, candied pecans, or sugared cranberries if desired. Slice and serve.