Brownies with extra oomph. Brown butter brings out a little caramel flavor plus I added extra vanilla, lots of big walnuts, two kinds of chocolate and espresso powder to make them more chocolatey. Great cold from the fridge or warm and gooey from the oven. They also freeze well.
Preheat oven to 350º. Line an 8" x 8" pan with parchment paper.
Melt the butter in a saucepan over medium high heat and cook until it stops sputtering and is dark brown. Remove from heat and add chocolate, cocoa powder, espresso powder, sugar, salt and vanilla and whisk until melted and smooth. Let cool for a few minutes then add eggs and stir until incorporated. Sprinkle flour over the top and mix in with as few strokes as possible, then add walnuts and fold in.
Scrape into prepared pan and bake for 45-50 minutes until the top is delicately cracked and a toothpick comes out with a little goo on the bottom third. Let cool for about 15 minutes then put in refrigerator for a few hours or overnight until cold. Cut into squares and serve.