Preheat oven to 350°F
To Make Crust:
COMBINE flour, 1/4 cup sugar and corn starch in a large bowl. Cut in butter until crumbly. Press into greased 13 x 9-inch pan.
BAKE in a preheated 350°F oven for 15 minutes until edges are lightly browned.
To Make Filling:
STIR together syrup, remaining sugar, eggs, salt and vanilla in a large bowl until blended. Add pecans and chocolate chips.
POUR over crust and bake an additional 35 minutes until filling is firm around the edges and slightly soft in center.
COOL completely, about 2 hours, before cutting into bars.