Brown Butter Brownies with Walnuts

Preheat oven to 325°F.
Line an 8x8-inch metal baking pan with foil, pressing the foil against the sides and leaving an extra two inches (for ease in lifting the finished brownies out of the pan). Coat foil with nonstick vegetable spray.
In a saucepan, melt butter over medium heat, stirring often, until butter stops foaming and browned bits form at bottom of the pan, about five minutes. Remove from heat and add sugar, cocoa, water, vanilla, and 1/4 teaspoon salt. Stir to combine. Let cool five minutes and add eggs to mixture, one at a time. Using a wooden spoon, beat vigorously after each egg. When mixture looks thick and shiny, add flour and stir until blended. Beat vigorously for one minute. Stir in nuts. Pour batter into prepared pan and place in oven.
After cooking for 10 minutes, remove from oven and sprinkle lightly with coarse sea salt. Return to oven and continue baking for another 15 to 20 minutes. These brownies can be made two days ahead, but be warned, the deans have never seen them last that long. Store airtight at room temperature.