In a bowl, combine all the ingredients. Shape the mixture into a 10-cm (4-inch) square on plastic wrap. Cover and freeze on a plate about for 20 minutes or until firm. Cut the butter into four strips. Keep in the refrigerator.
Preheat the oil in the deep fryer to 170 °C (325 °F). Place a rack on a baking sheet.
With a small sharp knife, insert the blade at one end of each breast half by cutting inside to create a large cavity without going through the flesh at the other end. Push a stick of butter in each cavity. Close tightly with a toothpick to seal. Season with salt and pepper. Set aside.
Place the flour, eggs, and breadcrumbs into three separate shallow plates.
Dredge each breast half in the flour and shake to remove any excess. Dip in the eggs and breadcrumbs. Dip again in the eggs and breadcrumbs.
Fry the breasts for about 14 minutes, two at a time. Drain on the wire rack. Serve immediately with green beans or a green salad.
It is important to tell your guests that there is a toothpick in the chicken and that the melted butter may squirt when cutting in the chicken.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.