This super fun, breadless sandwich recipe is over-the-top delicious! I made it with peppers because I think it’s tasty, and it also happens to be perfect for gluten-free grilled cheese!
Preheat a panini press. (See notes.)
Slice about 1-inch off the tops and bottoms of the peppers, including the stems. Then slice each one in half vertically. Use a paring knife to smooth out the inside of each half, and to remove the seeds and membranes. Set aside.
Spread half of them with the mustard and evenly distribute half of the cheese slices on top. Follow the cheese with the ham and arugula on top. Then add the remaining cheese, and "close" them with the remaining pepper halves, smooth side up.