The ingredients are straightforward (just the way I like it) and include Baking Mix, which is one of my favorite cookie bar conveniences (like Bisquick).
Recipe Ingredients: Semi-Sweet Chocolate Chips, Baking Mix (such as Bisquick) Sweetened Condensed Milk, Dark Brown Sugar
In a small microwave-safe bowl, combine sweetened condensed milk with 1 1/2 cups chocolate chips.
Heat at one-minute intervals -- stirring well after each -- until melted, smooth, and ingredients are fully blended.
In a medium size mixing-bowl, stir together melted butter, brown sugar, vanilla, eggs, and baking mix until ingredients are fully incorporated with one another. Stir in remaining chocolate chips.
Spread 2/3 of batter onto the bottom of greased 9x13 pan. Spread melted chocolate mixture on top -- fully cover the batter from side to side.
Spread those spoonfuls of batter as best as you can. It's okay if you still see the chocolate layer underneath some. That just makes for a prettier final bar.