Microwave chocolate and butter in large microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted. Beat whole eggs, yolks, sugar and flour with whisk until blended. Gradually beat into chocolate mixture.
Line 12 muffin pan cups with paper liners; spray with cooking spray.
Place 1 cookie, upside-down, in each cup; cover with batter.
Bake 8 min. or until cakes are firm around edges but still soft in centers. Cool in pan 1 min. Carefully remove cakes from pan. Invert into dessert dishes; remove paper liners.
