To make a gooey grilled cheese sandwich, you need a good melting cheese like Mahón; be sure to choose a young semi-soft variety rather than a hard aged one. Meaty lomo, a newly imported ham made from dry-cured pork loin accented with garlic and paprika, is definitely worth seeking out, though Serrano ham is a very acceptable substitute.
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2 ounces Spanish green olives, pitted and coarsely chopped (1/4 cup)
1 small garlic clove, minced
1 tablespoon minced flat-leaf parsley
1 teaspoon fresh lemon juice
Pinch of crushed red pepper
1 1/2 teaspoons extra-virgin olive oil, plus more olive oil for brushing
Eight 1/2-inch-thick slices peasant bread from a 1-pound loaf
6 ounces sliced young Mahón or other young, mildly tangy cow's-milk cheese, such as Edam or Gouda
3 ounces thinly sliced lomo ham or thinly sliced Serrano ham trimmed of all fat
In a bowl, combine the olives with the garlic, parsley, lemon juice, crushed red pepper and 1 1/2 teaspoons of olive oil.
Preheat a grill pan or panini press. Arrange the bread slices on a work surface and brush one side of each slice with olive oil. Turn the oiled sides of the bread face down. Spread the olive tapenade on four slices of the bread. Top with the sliced Mahón cheese and lomo ham and close the sandwiches with the remaining slices of bread. Grill the sandwiches over moderate heat, turning once until the bread is lightly toasted and the cheese is melted, 5 to 6 minutes. Transfer the ham-and-cheese sandwiches to a cutting board, halve and serve at once.