In a separate large bowl, cream the butter and sugar together until light and fluffy. Beat in the eggs, one at a time. Add vanilla.
Make each cake batter by pouring half of the butter/sugar mixture into the two separate bowls of flour. Mix both bowls until well combined and creamy. One will be for chocolate-coconut cake mix and one is for the pumpkin cake.
For the chocolate & coconut batter: Put 6 oz of chocolate in small bowl and microwave in 30 seconds increments or until melted. Cool for a few minutes and add to one of the cake batter bowls. Then add 1/2 cup of milk and 1/2 cup of flaked coconut. Mix and set aside.
For the pumpkin batter: Add 1 can of pumpkin and the pumpkin pie spice and cinnamon to the other butter/flour batter. Mix together until well combined.
Spoon half the pumpkin batter into the 12-cup bundt-cake pan. Drop the chocolate batter by spoonfuls over the pumpkin batter. Swirl a couple times with a butter knife. Repeat to spoon remaining pumpkin and chocolate batters into pan. Swirl again about 10 times back and forth all over the pan.
Bake for 50-60 minutes or until toothpick comes out mostly clean. Cool cake 10 minutes before turning it on a rack, then let cool completely.
Next put the other 6 oz of dark chocolate in a small microwave bowl with 2 tsp of milk. Microwave for 30 seconds, then stir. Spoon the chocolate glaze over the cake and top with toasted coconut. Let the glaze set for about 10 minutes before serving.
Keep cake covered for up to 3 days. Cake will remain moist.