Preheat the oven to 350° F.
Into a bowl, sift together the flour, baking powder, and salt.
With the help of an elder and using a double boiler, melt butter and chocolate.
In a mixing bowl, beat eggs. Add sugar to eggs a little at a time, beating well. Very slowly add the butter- chocolate mixture to it, little at a time.
Stir in flour mixture, blending well. Stir in vanilla and peanut butter.
With the remaining 2 tablespoons of butter, grease a 8-inch square pan and lightly flour it with reserved flour.
Evenly spread the brownie batter in the 8-inch pan.
Bake it for about 25 minutes, until the toothpick you insert in the center should come out with a few moist crumbs attached.
Cool in pan and cut into squares with a serrated knife with the help of the elder.
Enjoy it with your friends, warm or room temperature.