1 -package brownie mix
1 stick unsalted butter, melted
1/4 cup water
2 large eggs
2 cups semisweet chocolate chips
1 can sweetened condensed milk
2 teaspoons vanilla extract
1-2 tablespoons unsweetened cocoa powder, optional
Preheat oven to 350 degrees. Position a rack in the lower third of the oven. Spray the bottom only of a 13 x 9 inch baking pan with nonstick cooking spray or foil line pan.
Combine the brownie mix, melted butter, water, and eggs in a medium mixing bowl with a wooden spoon until just blended and all dry ingredients are moistened. Spread batter into prepared pan.
Bake for 20=30 minutes or until toothpick inserted 2 inches from side of pan comes out clean.
During last 10 minutes of brownie baking, prepare topping. Melt chocolate chips with condensed milk in a heavy saucepan set over low heat, stirring until smooth. remove from heat and stir in vanilla.
Remove brownies from oven and immediately spread with chocolate mixture. Transfer to a wire rack and cool completely. Chill for 1 hour in refrigerator to set topping. Cut into bars. If desired, sift cocoa powder over squares. Store in refrigerator.
Double batch for thick brownies.