Heat oven to 350°F. Mix flour, sugar and butter. Press in ungreased 13x9-inch pan. Bake 15 minutes.
Mix raspberries, orange juice and cornstarch in 1-quart saucepan. Heat to boiling, stirring constantly. Boil and stir 1 minute. Cool 10 minutes. Sprinkle chocolate chips over crust. Carefully spread raspberry mixture over chocolate chips.
Bake about 20 minutes or until raspberry mixture is set. Refrigerate about 1 hour or until chocolate is firm. For triangles, cut into 4 rows by 3 rows, then cut each square into 4 triangles.