Preheat your oven to 350 degrees Fahrenheit and generously grease your mini bundt cake pan with butter to make things easier when removing these little cakes.
In a bowl, whisk together the flour, sugar, baking soda, baking powder, cinnamon, and sea salt.
In a separate bowl, add together the hot water and cocoa powder----whisking until smooth.
In the bowl of an electric stand mixer, beat together on low speed---the eggs, milk, melted butter, and vanilla, scraping down the sides if needed. Add in the cocoa-water mixture and mix until combined.
Turn the speed to medium-low and add in dry ingredients, mixing until batter becomes smooth. Fold in the chocolate chips.
Pour the batter into each bundt cake cavity, about 2 Tbsps and using a butter knife, spread around evenly. NOTE: It makes things easier when I use a piping bag or ziplock bag.
Bake for 15-20 minutes, just until the center of each cake is cooked through. NOTE: You can use a toothpick or baking skewer to test this out; either should come out clean once inserted and removed.
Remove from the oven and let cool for about 15 minutes before removing them from cake pan to continue to cool completely.