Preheat oven to 325.
Combine first 3 ingredients in a medium bowl; add butter and vanilla, and beat at low speed with an electric mixer until blended. Stir in 1 cup chocolate chips.
Press dough into an ungreased 9-inch square pan; prick dough with a fork.
Bake for 20 minutes or until lightly browned. Sprinkle remaining 1 cup chips over top; spread to cover once chips have melted. Cut shortbread into 25 (about 1 3/4-inch) squares; cut each square into 2 triangles. Let cool 30 minutes in pan before removing.
Bake
2009, 2020