Preheat oven to 350°. Mix together the flour, 1/4 cup sugar
and 1/4 cup butter until crumbly. Press into a greased 8- inch
Bake for 12 to 15 minutes or until golden brown. Cool.
In heavy saucepan, melt 1/2 cup butter. Add the
corn syrup and the sweetened condensed milk. Bring to a boil and
cook for about 12 minutes, stirring constantly, until mixture turns a nice medium
caramel brown color. Do not let the mixture scorch. When it's very thick and begins to stick to the bottom of the pan as you stir, it's time to remove from the heat; add the vanilla. Stir to blend and pour over the crust.
Melt chocolate chips in a heatproof bowl over simmering water; spread over the caramel layer.
Chill until set, then cut into squares.