Combine first 4 ingredients in a large mixing bowl; beat at medium speed with an electric mixer 1 to 2 minutes.

Press half of cake mix mixture into bottom of an ungreased baking pan. Bake at 350 for 10 minutes. Remove from oven; sprinkle with chocolate chips, and drizzle with condensed milk. Sprinkle with remaining cake mix mixture. Bake at 350 for 30 minutes. Cool and cut into bars.