Prepare the red pepper sauce (this can be done the day before). Combine the ingredients in a blender. Pulse until you reach the desired consistency.
Prepare the chard in a medium sauce pan with a lid. Heat pan to medium and add oil. Once heated, add chard by the handful. It will cook down A LOT. Stir the chard, apple cider vinegar, and salt. Cook for 6-7 minutes. Take off heat and set aside.
Heat skillet to medium (we really like cast iron for this if it’s available, but if not use a non-stick pan).
Assemble the sandwich: one slice of Gouda first, top with bacon, then the apple, two spoonfuls of sautéed chard, and finally, more sliced of cheese. Top with the second slice of bread. Spread a thin layer of mayo on this slice. If you’re making multiple sandwiches, assemble them all before you start griddling.
Place the sandwich mayo side down in the skillet. Spread mayo on the bread slice now facing up and cook three minutes, or until bread is toasty brown. Turn and repeat. Your stove top and pan may require slightly cook times.
Serve with red pepper sauce for dunking.