Preheat oven to 350 degrees. Grease a 9x9 square baking pan.
In a mixing bowl, stir together the melted butter, brown sugar, vanilla, and egg. Add the flour and salt and mix until combined. Fold in the chocolate morsels. Spread the batter into the prepared pan. Bake in the preheated oven for 18-20 minutes, being careful not to over bake (you want the top of the blondies to be set, but the interior to look just slightly underdone). Allow to cool 5-10 minutes before slicing and serving.