In a medium bowl, whisk together dry ingredients.
Whisk in the milk and vegetable oil until all ingredients are combined and batter has no clumps.
Pour batter into a microwave-safe mug.
Add hazelnut chocolate spread in the middle of the batter or mini chocolate chips.
Place a paper towel into the microwave and set the mug on top.
Microwave mug cake for 70 seconds on high.
Carefully remove from microwave and enjoy!
