caramel chip bars

warning: this is naughty. there, i said it. but what i'm also saying is: decadent. my sister amy shared this recipe and i figure that i need to put some recipes for bars on here. it's the midwestern thing to do.

caramel chip bars
1/2 c. butter
32 caramels (the little square individually-wrapped ones, obviously unwrap them)
1 (14 oz.) can sweetened condensed milk
1 (18 oz.) package yellow cake mix
1/2 c. vegetable oil
2 eggs
2 c. semisweet chocolate chips
1 c. white chocolate chips
1 (1.5 oz.) heath bar, chopped

in a large saucepan, combine butter, caramel and milk; stir over medium-low heat until smooth. cool. in mixing bowl, combine cake mix, oil, eggs; mix well. stir in chips and heath (dough will be stiff). press 3/4 into greased 9x13". bake at 350 for 15 minutes. cool for 10 minutes.
pour caramel mix over crust. drop remaining dough by spoonfuls into caramel. bake for 25-30 minutes or until edges are golden brown. cool for 10 minutes; run knife around edge of pan. cool 40 minutes longer; cover and refrigerate for at least an hour or until serving. when you cut to serve, cut fairly small as these are rich!