Pre-heat your oven to 325° F and line a 9 by 13 inch pan with parchment paper.
In a large bowl, add your eggs and sugar and whisk until combined and has a foamy consistency.
In a separate bowl, add your melted butter and melted chocolate and stir until combined. I usually do this step in a large measuring cup.
Slowly pour your chocolate butter mixture into your sugar egg mixture. Stir until combined.
Add your vanilla extract and stir again.
Add in your flour, cocoa powder and salt and mix until just combined. Batter should be thick.
Pour your brownie batter into your baking dish lined with parchment. (Parchment helps remove the brownies from you pan and avoids sticking) Spread it out evenly and top with dark chocolate.
Melt your peanut butter in a microwave safe bowl and pour it over your brownie pan. Swirl it around with your brownie batter. Not too much though, you don't want to mix it in, just swirl it.
Bake in your oven pre-heated to 325° for about 25-30 minutes.
Remove from oven and top with flaky sea salt. Let cool.
Once your brownies have cooled a little, cut into squares.
Remove from pan, serve, share and enjoy!!