Preheat oven to 350 degrees F. Line an 8 inch square metal pan with nonstick foil.
In a small saucepan, melt the butter over medium heat. Add the sugar, reduce heat slightly and stir for about a minute or until shiny and sugar has dissolved. Remove from heat and stir in the cocoa powder and jalapeno oil. Let mixture cool for about 10 minutes.
While mixture cools, stir the flour, salt and baking powder together in a small bowl or measuring cup.
In a mixing bowl, gently whisk (do not beat) together the eggs and vanilla. Stir the chocolate mixture into the egg mixture until blended, then stir in the flour mixture. Let the mixture cool slightly if it is still warm, then stir in the walnuts and the chocolate chips.
Spread mixture in the pan and bake for about 28 minutes or until brownies appear set. Let cool completely. For a cleaner cut, chill before cutting.