Put the white chocolate chips and milk in an oversized microwave-safe mug. Microwave for about 40 seconds. Mix with a small whisk or fork until chocolate is totally melted.
Add flour, baking powder, and oil and stir until batter is smooth.
Crush the Oreos and mix into the batter.
Cook in the microwave for about 1 minute. Let cake cool a minute before eating.
Eat warm.
Recipe by Mandy's Recipe Box at https://mandysrecipeboxblog.com/cookies-and-cream-mug-cake/