Preheat your oven to 350 F. Prep a silicone bundt cake mold by lightly spraying it with baking spray to make sure there is absolutely no chance of the cake sticking. (see note)
In a medium-sized mixing bowl, combine the flour, cocoa, baking powder, baking soda, salt, and cinnamon. Set aside.
In the bowl of a stand mixer, beat the butter and sugar together for 1 minute until fluffy. Add in the milk, sour cream, and vanilla and mix to combine. Add in the eggs one at a time while the mixer is still running, mixing until smooth.
Add the flour mixture to the wet ingredients and mix for 1 minute. Then add in the hot water and mix for another 30 seconds.
Pour the batter into the prepared cake mold and place it on a baking sheet to keep the mold from wobbling. Bake for 70-80 minutes or until a toothpick inserted halfway between the wall and the tube comes out clean.
Remove the cake from the oven and let cool completely in the mold on a wire rack.
Once your cake is cooled, add the chocolate chips and shortening to a medium microwave-safe bowl. Heat in 30 second increments, stirring in between. Repeat until the chocolate is compaltely melted, about 1 1/2 - 2 minutes total.
Gently remove the cake from the silicone mold and wipe out the cake mold to ensure it is clean. Pour the chocolate into the mold and use a pastry brush or the back of a spoon to spread the chocolate around the entire mold as evenly as possible.
Carefully place the cooled cake back into the mold ensuring that you line it up with its initial grooves. Place into the freezer for at least 2 hours until the chocolate glaze is firm.
Remove the chocolate-covered cake from the silicone mold and place it onto a large plate for serving. (see note) Cut into 12 slices and enjoy!
Notes
If you don't have a silicone cake mold, that's okay. Grease and flour a standard bundt cake pan. Also, I recommend pouring the chocolate glaze over the cake instead of using the pan to "dip" the cake into the glaze. A regular pan doesn't let go of the glaze the same way a silicone cake mold does.
If there are any holes or cracks where the chocolate glaze is too thin after freezing, you may add another layer of chocolate by brushing the mold with leftover chocolate and placing the covered cake back into it and into the freezer to freeze again.