Start by preheating your oven to 350°F. Spray your bundt pan thoroughly with non-stick baking spray. Use a pastry brush to make sure every corner is coated. This prevents sticking later.
In your stand mixer bowl, sift the cake flour, cocoa powders, baking powder, baking soda, and espresso powder. Then whisk in the sugar and salt. Mixing these dry ingredients first helps evenly distribute the leavening agents.
In a separate bowl, whisk together the oil, eggs, buttermilk, and vanilla extract. Use room temperature ingredients for a smooth batter that bakes evenly.
Turn your mixer to low and slowly add the wet mixture into the dry ingredients. Once all wet ingredients are added, raise the speed to medium. Mix until everything is fully blended, scraping down the bowl sides.
Slowly pour in the hot water with the mixer on low. Once combined, turn off the mixer. Use a spatula to fold in the crushed Oreos gently. This keeps them from breaking down too much.
Pour the batter into your prepared bundt pan. Smooth the top and bake for 45 to 50 minutes. The cake is ready when a toothpick comes out clean from the center.
Let the cake cool in the pan for 10 minutes. Then flip it onto a wire rack and allow it to cool completely before glazing.