In a small bowl, whisk together your almond flour, baking powder and xanthan gum. Set aside.
In another microwavable bowl, melt your mozzarella in 30s increments until you can easily stir it (it took about 1 1/2 min for me in total).
Add your already whisked egg and your dry ingredients to the melted mozzarella and stir very well until a dough starts to form. At first the mozzarella may not completely stick to the other ingredients. This is okay, just begin to knead the dough like you would bread dough until the mozzarella is incorporated.
If the mozzarella still doesn’t want to blend into the other ingredients after a minute or two of kneading, place everything back in the microwave for 10-15s and then knead the dough again. Repeat this as needed until all ingredients are incorporated well and you can form a nice clean ball.
Roll out your ball of dough between two sheets of parchment paper about 1/8th of an inch thick. (Thin but still thick enough so it won’t fall apart easily)
Next take a glass or coffee mug and press it into the dough, rotating back and forth a few times and removing to cut circles. Cut 10 circles in total. (Take the dough scraps, put them back together and roll them out again to cut more circles).
At this time, you can also heat up your oil in a large wok or skillet to ~350* (anywhere between 350* and 375* is okay).
Back to the dough, evenly disperse the cheese between the middles of 5 of your circle cut-outs then top with the ham and a few dots of mustard or mayo (you can also gently spread the mayo or mustard over the middle first to make it easier)
Next take a circle of dough that doesn’t have filling and place it on top of one that does. Pinch the edges of both together using your fingers and then use a fork to fully seal them (I like to flip my sandwiches over and check that the under-side is also sealed well). Repeat this process for the rest of your pieces of dough.
Once your oil is at the correct temperature, set some paper towel aside on your counter and a wire rack for cooling your sandwiches.
To begin frying, gently place your sandwiches into the hot oil (I like to do two at a time). Cook for 1min to 1min 30s per side, flipping with a two forks. (You can usually tell when a side is down because it will start to form large air pockets/bubbles and turn golden brown).
Once the sandwiches are golden brown on both sides, you can remove them and set them on the paper towel to drain the excess oil and then onto the wire rack. Repeat this process with the remaining sandwiches. Then enjoy your fried ham and cheese sandwiches! (These are best served hot but you can also refrigerate the sandwiches and re-heat them in an oven on a baking sheet until crisp again).