In a food processor, combine pistachios, oregano, thyme, and garlic powder. Process until finely chopped and transfer to a shallow dish. Season both sides of tilapia fillets with salt and pepper. Brush honey mustard over both sides of tilapia and then transfer to pistachio mixture. Press mixture into both sides of fish.
Heat 1 tablespoon of the oil in a large skillet over medium heat. Add tilapia and cook 2 to 3 minutes per side, until fork-tender.
Heat remaining oil in a small skillet over high heat. Add prosciutto and cook 2 minutes, until golden brown. Add pine nuts and cook 1 minute, until nuts are golden brown. Add chard leaves, cover and steam 2 minutes, until leaves soften. Arrange chard mixture on a serving platter and top with Gorgonzola and serve with tilapia.