Chop garlic cloves then sprinkle with some salt and smash to make a paste. Set a large nonstick pan over medium heat. Add butter, oil and garlic and swirl pan. Add oyster crackers and chopped flat-leaf parsley and toss to coat. Spread out on a sheet tray, season with salt and pepper and sprinkle with shredded Parmigiano. Pop into the oven and bake for 25 to 30 minutes until golden and crispy.