Preheat oven to 350°F (180°C).
Wash, dry and chop the potatoes. Place into a large pot of cold, salted water and bring to a boil. Reduce heat and cook potatoes until fork tender, about 7-10 minutes. Remove from heat and drain. Transfer potatoes to a medium bowl and mash them with a fork. Set aside.
In a large bowl, combine flour, white and brown sugars, cinnamon, baking powder and salt. Stir in the mashed potatoes, oil, sour cream, vanilla and eggs.
Gently pour the cake batter into a bundt cake pan. Place into the oven and bake for 40 minutes. Remove from oven and transfer onto a cooling rack. Let cool completely.
In a microwave-safe bowl, heat milk on high for 90 seconds. Remove and stir in chocolate chips until smooth and melted.
Place the cooled cake onto a platter. Cover completely with the chocolate sauce and garnish with sweetened shredded coconut. Cut into 10 pieces. Enjoy!