For the brownies, preheat oven to 350 degrees. In a medium saucepan over low heat, melt butter and chocolate chips. Stir constantly and remove from heat when chips are fully melted. In the same pot, blend in the sugar. Then add eggs, blending fully one at a time. Add flour and salt and beat until air bubbles form in the batter.
Pour into a greased 9 X 13-inch pan. Bake for 20 minutes. Turn heat down to 325 degrees and bake for 10 more minutes.
Cool completely and then top with the cookie dough layer.
For the cookie dough layer, in a small bowl, cream butter and sugars until light and fluffy. Beat in milk and vanilla. Gradually add flour and salt. Stir in chocolate chips. Drop by tablespoonfuls over cooled brownies; carefully spread over top (this can be tricky but I found the best way is to slightly wet my hands and pat the dough down gently so it doesn’t pull up the brownies).