In a mixing bowl, mix sugar and the margarine together and beat until creamy with no lumps. Add egg whites and mix together until well blended. Add flour and blend until incorporated.
Divide into 1-ounce balls and press the dough balls into fluted brioche tins or cookie molds. Place into the preheated oven and bake for approximately 15 to 20 minutes or until the cookies are golden brown. (Take care NOT to burn). Unmold and set aside to cool on a rack. Store in an air-tight container until ready to use. Stores up to 1 month in a container or 3 months sealed and frozen.
Place the ricotta in a bowl and whip in the sugar, cinnamon and vanilla. Put the filling in a pastry bag with a star tip and set aside.
Fill each cookie shell with 1 ounce of the sorbet and form a teaspoon size ricotta star into the center of each cookie. Garnish each cookie with a mint leaf.