Preheat your oven to 180°C (350°F).
Sift the all-purpose flour, cocoa powder, baking powder, and baking soda together into a large mixing bowl. Set aside.
In a separate bowl, whisk the caster sugar and oil until the sugar dissolves.
Add the condensed milk, prepared coffee, and red gel food coloring. Mix until smooth and well combined.
Gradually add the dry ingredients to the wet mixture, stirring gently to combine.
Add warm water as needed to adjust the batter to a pourable consistency.
Grease a mini silicone bundt pan lightly with oil. Fill each cavity about ¾ full with the batter.
Bake for 20–22 minutes, or until a toothpick inserted in the center comes out clean.
Let the cakes cool completely before carefully demolding to avoid tearing the delicate bundt shapes.