Heat oven to 200° F. Line a rimmed baking sheet with paper towels. In a large bowl combine the stuffing, mashed potato, and two lightly beaten eggs. Form 8 equal sized patties. Heat 2 tablespoons of oil in a large skillet over medium heat. Add four of the patties to the pan and cook, flipping once, until they are deep golden on both sides, about 4 minutes total. Transfer patties to lined baking sheet, wipe pan clean and repeat the process with the remaining oil and patties. Place the baking sheet in the oven to keep patties warm.
Fill a medium pot with hot water. Line a rimmed baking sheet with parchment or waxed paper. Heat water over medium-low heat until tiny bubbles form on the sides of the pot and occasionally break the surface. Add the vinegar to the water. Working two at a time, crack eggs into two small ramekins. One at a time, slide eggs gently into the water. Cook for 3 to 4 minutes for slightly runny yolks. Carefully remove eggs from water with a slotted spoon and transfer to prepared baking sheet. Repeat with remaining eggs.
Divide the cakes among plates and top with baby spinach and turkey in an even layer. Carefully top with poached eggs. Spoon 2 tablespoons warm gravy over each egg and season with salt and pepper. Serve immediately.