Combine oats, flour, baking soda and salt in a medium bowl.
Cream butter, sugars, egg, milk and vanilla in large mixer bowl on medium speed until light and creamy. Gradually add flour mixture on low speed, mixing until blended. Stir in chocolate chips. Press dough firmly into greased 10" (25cm) springform pan or 12 1/4" x 1/2" (31cm x 1.3 cm) pizza pan.
Bake in preheated oven for 35 to 40 minutes in springform pan or 25 to 30 minutes in pizza pan, or until light golden. Cool in pan on wire rack. Cut into wedges to serve.