Step 1: Put the butter into a mug and microwave for 10 seconds to melt. (Skip this step if using oil).
Step 2: Add egg and milk lightly beat with a fork until combined.
Step 3: Add dry ingredients into mug and beat with a fork until thoroughly mixed.
Step 4: Stir through 1/4 cup of chocolate chips/candy into the batter.
Step 5: Place mug in the microwave and cook for 2-3 minutes on medium heat. (Cooking time may vary depending on microwave)