In a microwave safe mug or bowl (it'll puff slightly while cooking, so make sure the bowl or mug isn't so small that it'll overflow), mix the oat flour, cocoa powder, and stevia.
Add the applesauce, nondairy milk, and vegan chocolate chips, and mix thoroughly.
Microwave the mug cake for 2 minutes. Depending on your microwave you may like it a bit more cooked, so feel free to add more time if it still seems too loose in the middle.
Sprinkle with a few more chocolate chips, add any other toppings you like and enjoy!