Preheat the oven to 450℉.
In a bowl, mix together the flour, salt, parsley, garlic powder, sugar and baking powder. Then, add in the parmesan, then the buttermilk and stir until everything is combined.
Place the baking dish in the oven with the 6 TB of butter and allow to melt. This also preheats the baking dish to help with the crispy edges.
Once the butter is melted, remove the dish then add in the biscuits mix. Carefully spread it out in the baking dish. Now, cover the top of the biscuits with the mozzarella cheese, then using a knife, score the biscuits into 9 squares 3x3.
Place the dish back into the oven and bake for 20-25 minutes. The biscuits are done when the cheese is melted and starts browning a little. Ovens will vary but 20-25 minutes is typically a good time.
When done baking, remove from the oven. Brush the top of the biscuits with the topping, then allow to cool 10-15 minutes before serving