In a large bowl, combine the risotto with the Parmesan, cream, herbs, and egg yolk. Season with salt and pepper.
Cut the cheese into 16 cubes. Scoop up about 3 Tbsp of the risotto mixture and pack it around a cube of cheese to make a croquette, a ball the size of a Ping-Pong ball. Repeat to form 16 croquettes.
Put the flour, egg wash, and bread crumbs in 3 separate bowls. Dredge the croquettes in the flour, dip in the egg wash, and roll in the bread crumbs. Chill thoroughly, 2-24 hours.
Pour oil into a tall pot to a depth of 5 inches.
Heat the oil over medium-high heat until it registers 375°F on a deep-frying thermometer. Deep-fry the croquettes in batches, without crowding, until they are evenly browned, 4-5 minutes. Using a slotted spoon or tongs, transfer to paper towels to drain briefly.