1
: In bowl, whisk together flour, sugar, cocoa powder, baking powder and salt. Whisk in evaporated milk and oil until smooth; stir in chocolate chips.
2
: Pour mixture into 10 oz (300 mL) mug. Microwave on high for 60 seconds; top with marshmallows and microwave for about 30 seconds or until marshmallows have melted.
3
: Remove from microwave and sprinkle with graham crumbs; let cool slightly before serving.