Pumpkin & Chocolate Marble Bundt Cake

Preheat oven to 350 degrees F. Grease and butter a 12-cup Bundt cake pan. Set aside. Beat butter and sugar until creamy. Add in eggs one at a time, beating after each egg. Add in vanilla and mix. Separate the batter into two bowls.
In one bowl, beat in the pumpkin mixture. Stir together 1 3/4 cups of the flour, 1 teaspoon baking powder, 1/2 teaspoon salt and the pumpkin pie spice. Add flour to the bowl and mix just until incorporated. In a separate bowl, mix together 1 cup flour, 1 teaspoon baking powder, 1/2 teaspoon salt and the cocoa powder and then add alternating with the buttermilk to the second mixing bowl and mix just until blended.
Spoon half of the batter into a greased and floured 12-cup Bundt cake pan. Drop the chocolate batter into the pumpkin. Repeat by spooning pumpkin and chocolate until all batter is used. Run a butter knife through the cake mixture center of the pan several times. Then swirl by running the knife the other way in strokes 10 or so times around the entire pan.
Bake at 350 degrees F for 55-60 minutes. Allow to cool for 10-15 minutes before inverting and releasing the cake. Cover with warm chocolate glaze and allow to sit until glaze is set.
Chocolate Glaze
4 ounces chopped semisweet chocolate
1/2 cup heavy whipping cream
1 tablespoon butter
1 teaspoon maple syrup
In a double boiler, add chocolate, cream, butter and maple syrup. Melt and mix. Pour over warm cake.