Prepare an 8x8 or 9x9 baking dish by lining with foil. An 8x8 dish is what I use, but a 9x9 would work too - you'll just get "shorter" bars.
In a large pot, combine the chocolate chips, sweetened condensed milk and salt on low heat. Melt the ingredients while stirring often. Heat and stir until melted and smooth.
Stir in the Reese's Pieces. (You can save some for the top if you want).
Spread it out in the pan. Refrigerate until cool.
Remove and cut into squares. You can cut them as big as you want, but it's pretty rich, so a little goes a long way!
