Put the 4 oz of chocolate in a medium bowl and set aside.

In a saucepan, melt the butter over medium heat. Continue cooking, stirring often, until the butter foams and turns golden brown with a nutty aroma—about 5–7 minutes.

Preheat oven to 350 degrees fahrenheit

Remove butter from heat and pour melted brown butter along with the brown leftover bits in the pan into the bowl with the 4 oz baking chocolate. Quickly whisk until smooth. Let it cool slightly for 5 minutes.

Whisk in the brown sugar and white sugar until glossy. Add the eggs, one at a time, whisking well after each. Stir in the vanilla.

Add the flour, salt, and Dutch-process cocoa powder. Stir gently until just combined. Don't overmix.

Gently fold in the semi-sweet chocolate chips, reserving a handful to spread over the brownie right before baking.

Pour batter into a parchment-lined 8x8-inch pan. Dollop peanut butter on top ofth bronie bater ad us akie orskwe to swirl I it th surac of the batter. Don't go too far deep into the batter. Sprinkle remaining chocolate chips.

Bake at 350°F (175°C) for 20-25 minutes, or until the edges are set and the center has a slight jiggle. With a toothpick poke a hole in the center of the brownie and it's done if it comes out with moist crumbs (not wet batter)

Place on a cooling rack while brownies are in the pan for 15 mins. Then remove brownies from the pan by lifting the parchment paper and place back on the cooling rack to cool completely before slicing.