Preparation Line large baking sheet with foil. Puree both cheeses and thyme in processor until smooth. Season with salt and pepper. Place breadcrumbs and flour in separate bowls. Mix milk and egg in another bowl. Form cheese mixture into 18 walnut-size balls. Coat balls with flour. Dip into egg mixture, then bread crumbs, coating completely. Place on prepared baking sheet. (Can be made 4 hours ahead. Cover and refrigerate.) Pour vegetable oil into heavy large skillet to depth of 1 inch. Heat oil until thermometer registers 350°F. Fry croquettes in batches until golden brown, about 1 minute per batch. Using slotted spoon, transfer to paper towels. Arrange croquettes on platter and serve.
Preparation Line large baking sheet with foil. Puree both cheeses and thyme in processor until smooth. Season with salt and pepper. Place breadcrumbs and flour in separate bowls. Mix milk and egg in another bowl. Form cheese mixture into 18 walnut-size balls. Coat balls with flour. Dip into egg mixture, then bread crumbs, coating completely. Place on prepared baking sheet. (Can be made 4 hours ahead. Cover and refrigerate.) Pour vegetable oil into heavy large skillet to depth of 1 inch. Heat oil until thermometer registers 350°F. Fry croquettes in batches until golden brown, about 1 minute per batch. Using slotted spoon, transfer to paper towels. Arrange croquettes on platter and serve.