Heat oven to 350ºF (325°F for dark pan). Chop 1/2 cup of the cashew halves. In large bowl, break up cookie dough. Stir in chopped cashews and oats. In ungreased 9x9-inch pan, press dough evenly to form crust. Bake 12 minutes.
Meanwhile, in 1-quart saucepan, cook condensed milk and chocolate chips over low heat about 6 minutes, stirring constantly, until chips are melted and smooth. Stir in vanilla.
Remove partially baked crust from oven. Spread chocolate mixture evenly over crust. Sprinkle with remaining 1/2 cup cashews; press gently into chocolate.
Return to oven; bake 12 to 15 minutes longer or until edges and center begin to crack. Cool completely on wire rack, about 1 hour. Cut into bars.