01 - Preheat oven to 350°F. Thoroughly grease and flour a 10-12 cup Bundt pan, tapping out excess flour.
02 - Whisk together flour, baking powder, baking soda, salt, ginger, cinnamon, cloves, nutmeg, and allspice in a medium bowl; set aside.
03 - Beat butter, oil, and brown sugar in a large bowl until light and fluffy, about 3 minutes.
04 - Mix in molasses until fully incorporated.
05 - Add eggs one at a time, beating well after each addition, then blend in vanilla extract.
06 - Add half the flour mixture to wet ingredients and mix briefly on low speed until just combined.
07 - Pour in buttermilk and mix gently. Add remaining flour mixture and stir until smooth without overmixing.
08 - Pour batter evenly into prepared pan and smooth the surface. Bake 40–50 minutes or until a toothpick inserted into center comes out clean.
09 - Allow cake to cool in pan for 15 minutes, then invert onto a wire rack and cool completely.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth and pourable. Adjust milk quantity as needed.
11 - Drizzle glaze over cooled cake and let it set before slicing and serving.