8 tablespoons (1 stick) butter, plus a little more for greasing the pan
3ounces unsweetened chocolate, roughly chopped
1cup sugar
2 eggs
1/2cup all-purpose flour
Pinch salt
1/2 teaspoon vanilla extract, optional
Instructions
Heat the oven to 350°F. Grease a square baking pan with butter or line it with 2 overlapping pieces of parchment paper or aluminum foil and grease the lining.
Combine the stick of butter and the chocolate in a small saucepan over very low heat, stirring occasionally. (Or microwave them in a large microwave-safe bowl on medium for 10-second intervals, stirring after each.) When the chocolate is just about melted, remove the saucepan from the heat (or bowl from the microwave) and continue to stir until the mixture is smooth.
Transfer the mixture to a large bowl (or use the bowl you put in the microwave) and stir in the sugar. Then beat in the eggs, one at a time. Gently stir in the flour, salt, and the vanilla if you’re using it.
Pour and scrape the mixture into the prepared pan and bake for 20 to 25 minutes, until just barely set in the middle. Cool on a rack until set. If you used parchment, lift it out to remove the brownies. If not, cut them in squares right in the pan. Store, covered, at room temperature, for no more than a day.