Preheat oven to 450° Cut butter in with flour, cornstarch and soda. Combine with 1/2 of the yogurt, raisins and eggs, stir until just moistened. Shape into a ball and flatten on a cookie sheet into a 9 inch circle 3/4 inch thick. Bake for 7-10 minutes. Combine remaining yogurt with cream cheese and serve with warm scones.