Preheat oven to 350F, middle rack. Beat the eggs and sour cream together until well combined. Grease a bundt pan with melted butter. I find it’s best to paint it on with a pastry brush. Beat the eggs and sour cream together until well combined. Add all the other ingredients to the cake and mix well. The batter will be thick.
Bake for 38-45 minutes or until a wooden skewer comes out almost clean. While the cake is baking, make the frosting by placing the butter and cocoa in a pan and bring to a boil; whisking. Remove from the heat and allow to cool completely. Place the cooled chocolate in the bowl of a stand mixer fitted with the paddle attachment. Beat for 2-3 minutes or until it turns light in color. Slowly add in the sugar and mix to combine. Add in the cream slowly until it becomes thick and frosting consistency. Add in the extract and mix just to combine. If you want, add in the corn syrup and mix it in. This doesn’t alter the flavor but will allow the frosting to become more stiff. Place in the fridge to cool.
When the cake is done, remove it from the oven and place it on a cooling rack for 30 minutes in the pan to cool. When the pan is cool enough to touch, place a cooling rack on top and carefully flip the cake out of the pan onto the cooling rack. Allow to cool completely before frosting. Garnish with mini chocolate chips.