Preheat the oven to 350 degrees F. Generously butter a 13-by-9-inch baking pan or spray it with nonstick cooking spray.
Place the butter and chocolate in a medium-size saucepan over low heat and let melt together, stirring until smooth. Remove the saucepan from the heat and stir in the cocoa powder, sugar, and salt, then blend in the vanilla. Beat in the eggs one at a time, stirring to mix quickly so they don't have a chance to cook at all before they are blended in. Blend in the flour.
Scrape the thick batter into the prepared baking pan and smooth the top with a spatula. Bake until the edges just begin to pull away from the sides of the pan and a wooden skewer or toothpick inserted into the middle comes out clean, 25 to 30 minutes.
Let the brownies cool in the pan on a wire rack. When completely cool, cut them into 12 or 24 squares.
Photograph by Todd Coleman/The Mom 100 Cookbook
A bit of bad news, I'm afraid. You really need to let these brownies cool completely before you cut them or they will cut messily and not hold their shape very well. It's best to leave the house to avoid temptation. But, hey, they're for a bake sale. You weren't going to actually eat one? Oh, okay, that'll cost you $1.00. By the way, the brownies are so much better, both in terms of taste and consistency, when they are completely cool-in fact they're even better the next day, firm and amazingly moist inside, with that gorgeous lightly crackled top crust. I have heard that these brownies can be stored in a tightly sealed container for up to five days, but this may be just a rumor.
"The Mom 100 Cookbook" by Katie Workman (c) Workman 2012. Provided courtesy of Katie Workman. All rights reserved.