Preheat oven to 350 degrees F (180 degrees C). Generously grease and flour a 10-cup bundt pan or spray with baking non-stick spray; set aside.
In the bowl of your stand mixer fitted with a paddle attachment, combine the Devil's Food Cake Mix (1 package), Instant Chocolate Pudding (1 package), Sour Cream (1 cup), Egg (4), Water (1/2 cup), Vegetable Oil (1/2 cup), and Pure Vanilla Extract (1 teaspoon). Mix on low speed just until ingredients are blended, and then increase speed to medium and continue blending for 3 minutes. Fold in Mini Chocolate Chips (1 1/2 cup).
Pour the cake batter evenly into the prepared bundt pan, smoothing the top gently.
Bake for 15 minutes.
Reduce oven temp to 325 degrees F (160 degrees C) and continue baking for 30-40 minutes or until a knife inserted comes out clean.
Remove from oven. Let cool for 10 minutes.
Invert cake onto a serving platter, place your hand in an oven mitt and tap all around the bottom of the pan until the cake releases completely. Cool for an additional 30 minutes at room temperature. I recommend covering the cake with plastic wrap at this point and placing it in the refrigerator overnight or until you are ready to frost it – this will seal in the moisture!
Chop the Semi-Sweet Dark Chocolate (8 ounce) into small pieces. Place the chocolate in a small heatproof bowl.
Place the Heavy Cream (1 cup) in a small saucepan over medium heat and bring to a low simmer (small bubbles around the edge of the pan), stirring occasionally.
Once simmering, immediately pour the cream over the chocolate. Swirl the bowl to ensure that all of the chocolate is coated with the cream. Cover your bowl and leave it undisturbed for 5 minutes.
After 5 minutes, remove the cover and begin to slowly whisk the mixture, starting with small circles in the middle and working your way outward until you have a smooth, glossy frosting. Let cool at room temperature for at least 30 minutes.
Place the cake on a serving platter and pour the ganache evenly over the top of the cake. Add mini chocolate chips or sprinkles if you would like! The cake can be kept, covered, at room temperature for up to 5 days.