In a large microwave-safe mug, combine the oat flour, cocoa powder, sugar, baking powder, and salt.
Stir until there are no clumps.
Stir in the coconut oil, milk, and almond butter and mix until it is smooth. Drop the chocolate chips in the mug cake and stir to combine. Once set and combined, add a little water (a teaspoon or two) on top of the batter to keep it moist (don't mix it in).
Microwave on high for one minute. Remove and enjoy.