Preheat your oven to 325 degrees F.
Line an 8 x 8 inch pan with parchment paper. Spray a little non-stick spray on it as well.
Then, melt the butter and unsweetened chocolate together over low heat in a medium size saucepan. Stir the mixture until the chocolate is melted and the mixture is smooth.
Next, remove the saucepan from heat and add the sugar. Stir well.
Add the eggs and vanilla to the saucepan, stir until it’s smooth.
Then add the semi-sweet chocolate chips, flour and salt. Stir until well combined.
Pour the mixture into prepared 8 x 8 inch pan.
Add the peanut butter chips, milk chocolate chips and mini chocolate chips to the pan. Give the pan a quick tap on the counter to get out any bubbles and then place it in the oven on the middle rack.
Bake the brownies for about 35-45 minutes.
Once baked remove the pan from the oven. Allow to cool for 5 minutes then use the parchment to lift the brownies out of the pan and place on a cooling rack.
Cut into squares if using a square pan. Cut into slices if using a round pan.
Serve with a big old peanut butter smile.