Brown Sugar Cookie Bars

I finally made them today. Here's the recipe:

1/4 c. butter
1 egg, beaten
3/4 c. all-purpose flour
1 tsp. baking powder
1/2 tsp. vanilla
*Optional* 1/3 c. chocolate chips or 1/3 c. chopped nuts

Preheat oven to 350 degrees. Grease an 8" square baking dish. Melt butter in a small saucepan. Remove from heat and add brown sugar. Stir until smooth and then add egg mixture. Stir together flour and baking powder and add to mixture. Stir in vanilla. Add optional ingredients last and mix well. Spread into baking dish and bake 20-25 minutes. Cool before serving.