Start by combining oats, cocoa powder, salt, and cinnamon in a small bowl. Then, mix in the flaxseed egg, applesauce, maple syrup, vanilla extract, oat milk, and espresso. Stir the ingredients well, and transfer the mixture to an oven-safe dish. Bake for 25-35 minutes at 350°F. After baking, spread a thin layer of nondairy yogurt on top and dust it with cocoa powder. Now, savor the deliciousness!