In a small bowl combine: flour, sugar, cocoa, baking powder and salt. Add egg, milk and vegetable oil. Whisk to combine.
Transfer 1/4th of the mixture to a regular sized coffee mug. Drop one mini snickers into the center. Top with another 1/4th of the cake mixture. Drop the caramel into the center. Top with another 1/4th of the cake mixture and another snickers. Top with the remaining cake mixture.
Place mug in microwave and microwave on high for 1 minute and 15 seconds to 1 minute and 30 seconds, microwaving it in 30 second increments to prevent it from spilling over. Check mug cake, if batter is still too gooey, microwave an additional 30 seconds. But be careful! You want the mug cake to still be a tad bit gooey and not dry/overcooked.
Top with whipped cream, roasted peanuts and salted caramel sauce. Enjoy!
The cake will rise significantly while microwaving. To prevent it from spilling over, make sure you microwave it in 30 second increments. Also, using a tall coffee mug is recommended.