1) Put each chicken breast between two pieces of cling film and pound to 1/2cm thickness, tapering thickness along the edges to 1/4cm. Set aside until needed.
2) Combine the panko and garlic salt in a small bowl and drizzle with oil; toss until coated. Heat a large non-stick frying-pan over medium-high heat. When the frying-pan is hot add the panko and toast until light golden, stirring constantly. Pour the toasted panko into a shallow dish.
3) In another shallow dish, whisk together the egg whites, milk, cornflour and mustard.
4) Line a roasting tray (with 2.5cm sides) with foil (to catch any juices) then set a large wire rack over foil. Remove cling film from chicken. Put the chicken on a work surface and sprinkle with salt and peppercorns; rub into the flesh.
5) In a small bowl stir together the prosciutto, fontina, blue cheese and chopped basil. Divide the mixture into six portions. On each breast, put a portion of the mixture on the bottom half and toward the centre. Roll the bottom edge of the breast over the filling then roll up tightly, tucking in the sides. Press firmly on the seam to secure. Roll the chicken in the egg white mixture to coat, then roll in the panko crumbs, pressing firmly. Arrange the chicken on the wire rack in the pan, spacing equally. Let rest for 20 minutes.
6) Preheat the oven to 180&;degC/Gas 4.
7) For the chutney, in a heavy 1-litre saucepan add the butter and let it melt over medium-high heat. Add the onion and cook until tender, stirring often, about three minutes. Stir in the vinegar, sultanas, ginger, brown sugar, Worcestershire sauce, curry, salt, nutmeg and blueberries. Bring the mixture to a boil, then reduce the heat to low and simmer for 15 minutes, stirring occasionally. Remove from heat and slightly mash the blueberries with a potato masher. Cover the pan and set aside.
8) After resting the chicken for 20 minutes, put the pan in the preheated oven and bake until an instant-read thermometer reaches 71C when inserted into the centre of the chicken roll, about 40 minutes. Remove from oven and let the chicken to rest for 5 minutes before serving. Transfer the chicken to a serving platter and serve topped with the chutney, (no need to reheat). Garnish with basil leaves and serve.
Cook's Note: The chutney can be made ahead and is just as delicious cold or warm over the chicken.
A viewer, who may not be a professional cook, provided this recipe. The Food Network Kitchens chefs cannot make representation as to the results.