From: Annie's Eats (adapted from Baker's Illustrted)
If you like thick (tall) brownies that are somewhere between fudgy and cakey, these might be just the brownies for you. I actually would have preferred these to be a little thinner, but the people I made them for really enjoyed them. I thought the flavor was really good, and I would make them again, but I personally might try to find a pan that was a little larger, like 9x9 instead of 8x8. The texture of the brownie was really good, and apparently they went perfectly with the dark stout beer everyone else was drinking with them.
5 oz. semisweet or bittersweet chocolate, chopped
2 oz. unsweetened chocolate, chopped
8 tbsp. unsalted butter, cut into quarters
3 tbsp. cocoa powder
3 large eggs
1¼ cups (8¾ oz.) sugar
2 tsp. vanilla extract
½ tsp. salt
1 cup (5 oz.) all-purpose flour
Place an oven rack in lower-middle position and preheat the oven to 350° F. Line an 8-inch square baking dish with foil and spray lightly with nonstick cooking spray; set aside.
In a heatproof bowl set over a pan of barely simmering water, melt the chocolate and butter, stirring occasionally until smooth. Whisk in the cocoa powder until smooth. Set aside to cool.
In a medium bowl, combine the eggs, sugar, vanilla and salt; whisk until combined, about 15 seconds. Whisk in the warm chocolate mixture until incorporated. Then stir in the flour with a wooden spoon until just combined. Pour the mixture into the prepared pan and spread with a spatula to make an even layer. Bake until slightly puffed and a toothpick inserted in the center comes out with a small amount of sticky crumbs clinging to it, 35-40 minutes. Transfer the pan to a wire rack and let cool to room temperature, about 2 hours.
Remove the brownies from the pan using the foil and transfer to a cutting board. Cut into squares as desired. Store in an air-tight container.