Rachael Ray's Best Basic Brownies recipe always works!
Of course, I add chocolate chunks. As far as cocoa power, I like Scharffen Berger and Guittard. Both are wonderful. Needless to say walnuts are always an option in my brownies.
Cooking time: This will actually vary with your oven, with the size of your pan and lots of other variables. Stick a toothpick in. If it comes out way to gooey, they're not done. These brownies are a bit chewy, so you'll have to make your own decision about gooey-ness. Also some people like vanilla in their brownies. It's all a matter of taste, so if you decide to use a tiny bit of vanilla, add it to the wet ingredients.
2 cups sugar
1 1/2 sticks melted unsalted butter
1/2 teaspoon salt
1 cup unsweetened cocoa powder
1 cup flour
Preheat the oven to 350°. Grease a 9-by-9-inch baking pan. In a large bowl, combine 2 cups sugar, 1 1/2 sticks melted unsalted butter and 1/2 teaspoon salt. Whisk in 3 eggs, 1 at a time. Stir in 1 cup unsweetened cocoa powder and 1 cup flour. Transfer the batter to the baking pan and bake until just set, 25 to 30 minutes; let cool.