How to Make It
Butter each slice of bread and sprinkle with Parmigiano, pressing to help it adhere. Invert the slices onto a work surface, cheese side down.
Top 4 of the slices with the Gruyere, ham and pickles. Mix the mustard and preserves and spread on the remaining 4 slices of bread.
Close the sandwiches and griddle over moderate heat, turning, until golden, crisp on the outside and melted inside, about 3-5 minutes. Cut in half and serve right away.
Or use a panini press for about 4 minutes.