Place ribs in a roasting pan and de-glaze the sauté pan with the Guinness making sure to scrape all brown bits from the pan. Pour the beer mixture over the ribs and add the beef stock, cover with aluminum foil and braise for about 3 hours
Thoroughly scrub the potatoes making sure all dirt is removed. Working with the potato parallel to the cutting board, slice perpendicularly spacing about 1/8’ apart and make sure to not cut all the way through
Place the potatoes on a shallow sheet pan lined with aluminum foil. Spread apart the slices and brush a melted butter in between each piece reserving about 2 tbsp. Sprinkle each piece with salt & pepper as well. Bake potatoes for about 45 minutes then brush with remaining melted butter and dust with chopped parsley
Once the ribs are fork tender, strain the braising liquid into a small saucepan and reduce on medium heat until reduced by half. Allow the reduction to cool and dip the ribs in to coat.
Once the reduction has cooled, place the softened butter in a food processor and process until doubled in volume. While the machine is running, add the reduction 1 spoonful at a time until done: