Mix together the brown sugar and butter in a large bowl. Add the egg and mix together. Add the flour, vanilla and salt and mix together well. Spread the dough onto a baking sheet to a thickness of 1/4 to 1/2 inch.
Bake until slightly brown, 15 to 18 minutes. At this point, pull the sheet out of the oven and sprinkle the chocolate chips evenly over the top. Return to the oven for 1 minute. Remove and spread the melted chips over the top. Sprinkle on the desired toppings, and then chill to set. Cut into squares.