In a mixing bowl, whisk the crushed garlic into the heavy cream, and set aside.
In a bowl with 4 tablespoons water, add the potato slices and cover, then microwave for 3 minutes. Drain.
Grease a mug with a generous amount of butter and add mozzarella. Next, begin to layer the potatoes, seasoning with salt, black pepper and Parmesan every few layers. Pour the garlic cream over the potatoes.
Place in the oven for 20 to 30 minutes, or until the potatoes are completely tender.
Flip the mug upside down on a plate, release the potato gratin and sprinkle chives on top. Serve, and enjoy.