In an oversized microwave-safe mug, add all ingredients. Whisk with a small whisk until smooth.
Place mug into microwave and cook at full power for 1 minute. Check on the pie. The edges of the pie should look cooked but the center is still uncooked.
Cook in the microwave again at 30 second intervals. I needed to do this twice (so a total cooking time of 2 minutes for my pie), checking after every 30 seconds until the center looks cooked and edges of the pie are starting to pull away from the mug. It is okay if the surface has a few trace wet spots. That is okay as long as the center of the pie looks cooked. Be careful not to overcook your pie. Keep in mind your pie will continue to cook in the mug for a little bit after you remove it from the microwave, so the wet spots on top should disappear once the pie cools.
Let the pie cook fully before eating. You can top with whipped cream if desired. The pie can be eaten straight out of the mug or you can also plate it. For plating tips, see post.