Preheat the oven to 350 degrees Fahrenheit. Prepare an 8x8 baking dish with parchment paper.

In a saucepan, brown the butter for the brownie batter in a pot. Stir continuously until the melted butter begins to create brown bits at the bottom of the pot and give off a nutty scent.

Add the 4 ounces of the chopped chocolate bar immediately to the hot butter and mix together until completely melted. Remove from the heat.

In a separate bowl, combine the sweetened condensed milk, sugar, eggs, and vanilla. Beat until thoroughly incorporated with a whisk.

Pour in the brown butter and melted chocolate mixture and mix together until combined

Fold in the cocoa powder, flour, and salt until combined. Use a rubber spatula, not a mixer to ensure you don’t overmix.

Pour the batter into the prepared baking dish. Sprinkle the other 4 ounces of the chopped chocolate bar on top.

Bake in the oven for 40 -45 minutes or until a toothpick comes out clean.

Let cool for 30 minutes before cutting.