I got this recipe back in high school, from my fabulous boss Pam at the library. I'm not a huge fan of chocolate, and this lovely mix of brownie texture and gooiness without all the chocolate is wonderful!
In a heavy saucepan, over low heat, melt the butter. Remove from heat and add the brown sugar. Mix well and cool slightly. Add eggs, one at a time, beating after each addition. Add vanilla and stir again.
In a large mixing bowl, sift flour, backing powder, and salt. Add brown sugar mixture and stir well. Add chocolate chips and/or walnuts, if using.
Spread evenly in a buttered 9 x 13 pan, and bake in a preheated 350 F oven. Test often with a toothpick or cake tester, as they are still quite blond when done. Cool slightly and cut into bars.