- Begin by preheating your oven to 350°F (175°C). Thoroughly grease a standard bundt pan with shortening, ensuring all crevices are coated, then dust lightly with flour, shaking out the excess. This prevents sticking and ensures a smooth release. 
- In a large mixing bowl, combine the sugar, flour, baking soda, salt, and cinnamon. Set this dry mixture aside for now. 
- Melt the butter over medium heat in a medium saucepan. Once melted, whisk in the oil, cocoa powder, and water. Bring the mixture to a gentle boil while stirring constantly to blend the ingredients. 
- Carefully pour the heated cocoa mixture into the bowl with the dry ingredients. Stir until just combined. 
- Add the buttermilk, eggs, and vanilla to the mixture. Using a whisk, blend everything together until smooth. Gently fold in the mini chocolate chips, if you're using them. 
- Transfer the cake batter into the prepared bundt pan, ensuring it's evenly spread. Bake for 45-55 minutes, or until a toothpick inserted into the center emerges with just a few moist crumbs. 
- Once done, allow the cake to cool in the pan for 5 minutes before inverting it onto a wire rack to cool completely.