For the fool: To a medium saucepan, add the papaya, pineapple and sugar. Cook over low heat, mashing with a fork, for 10 to 15 minutes, or until the mixture is the consistency of a chunky puree. Remove the mixture from the heat and refrigerate until well chilled. Using an electric mixer, whip the heavy cream. Gently fold the heavy cream into the fruit mixture. Refrigerate for several hours.
For the hazelnut florentine cups: Preheat oven to 350 degrees F. In a food processor, pulse the hazelnuts until they resemble fine crumbs. Be careful not to over grind and create a paste. In a small saucepan, melt the butter. Add the brown sugar and the corn syrup. Bring to boil. Remove from the heat and add the ground hazelnuts, and flour. Mix well. Drop tablespoonfuls onto a greased cookie sheet several inches apart, these cookies will really spread out. Bake for 5 to 8 minutes or until brown around the edges and lace-like in appearance. Remove from the oven and immediately and carefully shape the cookie over an upside down 8-ounce glass to form a small bowl. Allow to cool for a few minutes. Transfer to wire rack. Place chocolate chips in a small bowl. Place the bowl over a pot of barely simmering water, and stir until the chips are melted. Once the chocolate is melted, paint the inside of the florentine cups with a thin layer of chocolate. Allow the chocolate to dry.
To finish: Place a large spoonful of the fool into each florentine cup. Garnish with a sprig of fresh mint and chopped, toasted hazelnuts.