- Portion size 8 servings
Cut chicken in half horizontally almost but not all the way through; open like book. Brush with mustard; sprinkle with pepper and salt. Lay 1 prosciutto slice on each breast; fold breast over to enclose.
Place 1 sheet of phyllo on work surface, keeping remainder covered with damp towel to prevent drying out. Brush with butter; top with second sheet. Centre 1 breast on phyllo about 2-inches (5 cm) from short edge; fold edge over chicken. Fold sides over and roll up. Place, seam side down, on greased rimmed baking sheet; brush with butter. Repeat with remaining chicken. (Make-ahead: Cover with plastic wrap and refrigerate for up to 8 hours.)
Bake in 350°F (180°C) oven for about 45 minutes or until golden and chicken is no longer pink inside.
In large heatproof bowl or top of double boiler, whisk egg yolks until pale; whisk in stock and vermouth. Place over simmering water; whisk for about 8 minutes or until thickened and frothy. Whisk in parsley, basil, oregano, lemon juice, salt and pepper. Serve with chicken bundles.