Preheat oven to 350 degrees F (175 degrees C). Grease 2 mini muffin tins generously with cooking spray.
Combine devil's food cake mix, eggs, chocolate pudding mix, vegetable oil, and 1/4 cup water in a large bowl. Mix with a wooden spoon until batter is thick and smooth.
Pour batter into the prepared mini muffin tins.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 9 to 10 minutes.
Let mini cakes cool in the tins for 1 to 2 minutes. Transfer to a wire rack.
Stir confectioners' sugar, 1/4 cup water, and cocoa powder together in a bowl to make glaze.
Dip tops of the mini cakes in glaze and place on a large sheet of waxed paper. Cool completely before serving, about 10 minutes.
