Preheat the oven to 375°F.
In a medium bowl, whisk together the almond flour, grated parmesan, garlic powder, dried parsley, sea salt and black pepper.
In a second small bowl, whisk the egg.
Melt 1 tbsp of the butter in a cast iron skillet over medium heat.
Dip one piece of chicken in the egg, letting the excess drip off.
Press the chicken into the almond flour mixture until fully coated on both sides.
Cook 4 minutes per side, until golden. Almond flour browns faster than breadcrumbs, so watch it and pull the heat back if it darkens early.
Set the browned chicken on a plate. Add another tablespoon of butter to the pan and repeat with the remaining thighs.
Spread 1/2 cup of the marinara across the bottom of a baking dish.
Arrange the chicken on top of the sauce in a single layer.
Spoon the remaining marinara over the chicken.
Lay a slice of mozzarella on each piece.
Bake 20 minutes, until the cheese is melted and bubbling and the chicken reaches 165°F internal.
Remove from the oven, garnish with chopped fresh thyme, and rest 5 minutes before serving.