Here's a recipe for Man Catcher Brownies - the name makes me cringe, but the end product is very much worth it. I've made them about 8-10 times, and they always get raves. It's from the Washington Post, as far as I know; but I'm too new to post a link so here's the recipe in all its glory.
Man Catcher brownies
12 ounces (3 sticks) unsalted butter
2 cups cocoa powder, sifted (natural or Dutch process)
6 eggs (yes, six eggs)
2 cups sugar
2 cups packed light brown sugar
2 tablespoons vanilla extract
2 cups flour
1 teaspoon salt
Preheat oven to 350. Melt butter in saucepan, remove from heat and add cocoa (I usually use Dutch processed). Let it cool slighty. Whisk together the flour and salt; set aside. Whisk eggs, sugar, vanilla together and add to chocolate mix. Gradually add the flour mix. Line a 13 x 9 pan with buttered parchment paper or aluminum foil; spread batter in lined pan. Bake 40-45 minutes until a crust forms on top. Cool, then cut as desired. The brownies are very dense and super-rich.
I also use the Double Chocolate Brownie recipe, which everyone also loves, from the Wellesley Cookie Book; but that takes melted chocolate chips rather than cocoa powder.