01 - Preheat oven to 350°F. Thoroughly grease and flour a 10 to 12-cup Bundt pan, removing any excess flour.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, salt, and all spices until combined.
03 - Using an electric mixer, beat butter, oil, and brown sugar until light and fluffy, about 3 minutes.
04 - Add molasses to the creamed mixture and mix until fully incorporated.
05 - Beat in eggs one at a time, ensuring each is fully blended, then mix in vanilla extract.
06 - Add half of the dry ingredients to the wet ingredients and mix on low until just combined.
07 - Pour in the buttermilk and gently mix, then add the rest of the dry ingredients, blending until smooth without overmixing.
08 - Transfer batter evenly into the prepared Bundt pan, smooth the surface, and bake for 40 to 50 minutes, or until a skewer inserted in the center comes out clean.
09 - Allow the cake to cool in the pan for 15 minutes before inverting onto a wire rack to cool completely.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth and slightly thick but pourable. Adjust milk quantity as needed.
11 - Drizzle glaze over the cooled cake, letting it cascade down the sides. Allow glaze to set before slicing.