Preheat oven to 350°F (175°C). Grease a 10-inch bundt pan and place it on a baking sheet.
In a large mixing bowl, cream together granulated sugar, brown sugar, and butter until light and fluffy (1–2 minutes). Add eggs, sour cream, and vanilla, mixing until smooth.
In another bowl, whisk together flour, cocoa powder, cinnamon, baking soda, and salt. Gradually mix dry ingredients into wet ingredients in two additions, alternating with warm water. Mix until just combined.
Pour the batter into the prepared bundt pan and bake for 50–60 minutes, or until a knife inserted in the center comes out with a few moist crumbs. Cool the cake for 20 minutes before inverting onto a rack.
For the coconut frosting, combine sugars, butter, egg yolks, and evaporated milk in a saucepan. Heat over medium, stirring until thickened and bubbling. Remove from heat, add vanilla, pecans, and coconut. Let cool completely.
For the ganache, heat heavy cream in a saucepan until steaming. Pour over chocolate chips, let sit for 2 minutes, then whisk in salt and vanilla until smooth.
Pour or drizzle ganache over cooled cake. Spread coconut frosting on top. Garnish with toasted pecans and coconut if desired.