Start by taking a pot and melting your butter then add the brown sugar. Continue mixing until the sugar is completely mixed in with the butter and let it boil for one minute. Add the dark chocolate chips and continue mixing until the chips melt.

Turn off the heat and add the condensed milk, vanilla and expresso powder. Then rapidly mix the eggs in to make sure they completely combine with the mixture.

In a separate bowl sift together the flour, cocoa powder, baking powder and salt. Then add the dry ingredients to your chocolate mixture and blend together. Add the oil and continue mixing. At this point, you can add your walnuts if you are using. This is optional.

Preheat your oven to 350 degrees. Greese your baking pan and pour the mixture between. Take a spatula and flatten the mixture into the pan. Place it in your preheated oven and bake it for 30 minutes.

Optional: As soon as you take it out of the oven, you have the option of adding more toppings. Do this while the brownies are still hot so the toppings will set in.