To give you an idea of what we’re going to do, picture that we are going to make sandwiches. But instead of bread, we’re going to use veal fillets. Easy peasy.
Take one of the fillets and smash it with a stone or a hammer (if you don't have one, you can use the bottom of a thick glass, but be careful!). Now do the same with the second fillet.
Lay a slice or two of cheese on top, covering it completely. Add another layer of jamón serrano. Alternatively you can use normal ham.
Place the second fillet on top. If you are going to make more than one Cachopo, use two fillets with similar dimensions. Press the borders with a fork, closing the interior of both fillets as much as possible. Some people use a toothpick to pierce both fillets to ensure that they will stay closed during the next couple of steps.
Prepare an assembly line with three plates. Place flour in the first one, whisk a couple of eggs in the second one, and add some breadcrumbs into the third. Brush your Cachopo carefully following this order (flour, egg and breadcrumbs) on both sides. The perfect balance is when your Cachopo is entirely covered in breadcrumbs, but the layer is as thin as possible, so that it will absorb less oil.
Pour plenty of oil in a big frying pan over medium-high heat. We want the oil to be hot, but not too hot because that would mean our Cachopo would be burnt on the outside and raw on the inside. Fry your Cachopo for about 2-3 minutes on each side.
Remove it and place it on a paper towel, to release the extra grease. Serve with some french fries or peppers.