Preheat oven to 350 degrees. Melt the chocolate chips and butter together over low heat on the stove, being sure to stir frequently. Alternately, you can heat the butter and chocolate chips in the microwave in 30-second increments, stirring between each heating until smooth. When completely melted and incorporated, set aside to cool slightly.

In a separate bowl, mix together the eggs and sugar. Add the vanilla and the melted chocolate mixture and stir.

Add the flour, baking powder, and salt. Mix well. Add nuts if desired.

Pour into a greased 9x13 pan and bake for 35-45 minutes, or until a toothpick comes out of the middle with just a few crumbs.

Remove from the oven and let cool before cutting into 2-inch squares. Makes 24 brownies.