Grate or shred the 1/2 stick of frozen butter and transfer it back to the freezer until time to add it to the batter.
In a small bowl whisk together the warm water and honey or inulin and sprinkle the yeast over the top.
Set yeast mixture aside in a warm place (90-105 degrees) to activate while preparing the other ingredients.
To the bowl of your stand mixer whisk together the egg white powder, gelatin, cream of tartar, salt and allulose and set aside.
Whisk the arrowroot powder in to the warm yeast and water mixture.
Combine the yeast mixture with the egg white powder mixture and whisk by hand until all the dry ingredients are moistened.
Start the mixer with the whisk attachment on low speed. Gradually increase the speed until full. Mix on full speed for 5-15 minutes or until stiff peaks form.
Reduce speed to low and stir in the frozen butter shreds just until combined.
Portion the batter into the wells of a greased bun pan or shape the batter into bun shapes onto a lined cookie sheet.
Allow the buns to proof in a warm spot (90-105 degrees) for 1 hour.
In the meantime, preheat your oven to 325 degrees.
Bake in the preheated oven for 18-22 minutes until browned and cooked through.
Remove the buns from the oven and allow to cool for 5-10 minutes before removing from the pan.
Slice 2 of the buns down the middle and set aside.
In a small bowl or jar whisk together all ingredients and store in the refrigerator until time to use.
In a medium bowl combine the pork rind crumbs, gelatin powder, egg white powder and seasonings.
In a separate bowl whisk together the egg and heavy cream.
One at a time, dip each fish filet into the wet mixture first and then toss in the breading mixture.
In a large frying pan heat about 1 cup of bacon grease or other frying fat of your choice on medium heat until it just begins to smoke
Cook breaded fish for 2-4 minutes per side in the hot oil. Cook time depends on the thickness of the fish so always check for doneness
Remove from the pan to a paper towel lined plate or wire rack.
On the bottom half of each bun place one piece of cheese and then a fish filet.
Scoop about a tablespoon of tartar sauce on top of the fish and top with the top half of the bun.
Enjoy immediately!