Divide the butter between two microwave-safe mugs or deep bowls (make sure they hold at least 10 oz. each).

Microwave each on low until butter is melted (about 10 seconds each).

Divide the crushed gingersnaps into the melted butter in each mug and press the crumb crust into the bottom of the mugs or bowls.

In a separate small bowl, whisk together the sweet potato puree, eggs, milk, brown sugar, and pumpkin pie spice. Divide between the mugs.

Microwave each mug separately on full power for 2 to 5 minutes, or until a knife inserted in the center of the mug pie comes out clean.

(Cooking will vary from microwave to microwave and with the size and shape of the mug. Begin cooking for 2 minutes. Continue cooking each pie for 30 seconds at a time until they’re done.)

Using an oven mitt, carefully remove the mug from the microwave.

Let the pies stand for a couple of minutes to cool.

Top with whipped cream (optional). Then EAT!!!