In a small sauce pot combine chocolate chips, sweetened condensed milk, butter, salt and vanilla. Turn to medium low heat and stir until completely melted and creamy. (I have a gas range. With the direct flame I had to reduce to my heat to low while melting.)
Divide the dough into two portions, with one portion having slightly more than the other. Use the portion with slightly more as the bottom crust. Press into a prepared 9×13 inch pan.