1. Preheat the oven to 375 degrees F.
2. Grease a 9 x 13 inch baking pan.
3. In an electric mixing bowl, cream the butter. Add sugar and cream it with the butter until smooth.
4. Stir in the vanilla extract and beat until well combined.
5. Add the eggs one at a time and continue beating at high speed.
6. Add the semi sweet chocolate chips and beat on medium speed until well combined.
7. Stir in the flour and baking powder mixture and beat until well incorporated.
8. Take the greased pan and spread the batter evenly in the pan. Bake it in the preheated oven for 16 - 20 minutes or until a toothpick inserted comes out clean.
9. After 16 minutes, remove the baking pan and sprinkle it with marshmallows, pecans and semi sweet chocolate chips. Bake this in the oven for another 2 minutes or until the marshmallows begin to melt.
10. Once done, remove and set it aside to cool. Using a wet knife make slices of the rocky road bars.