To get the proper texture, do not use an electric mixer. You
do not need to sift the flour, but spoon the flour into the
measuring cup so as not to pack it down too much. Use the
spoon handle to brush away extra flour and thereby ''level''
the top of the measuring cup.
Start to finish: 7 minutes preparation, plus approximately 20 to
25 minutes' baking time and 20 minutes' cooling time.
Heat the oven to 350. Grease a 9-inch-by-12-inch baking pan
well with butter. Set the pan aside.
Melt the 2 sticks of butter in a 2-quart microwave-safe bowl
covered with a paper towel. Remove the bowl from
microwave and add the brown sugar. Stir well. Add the baking
powder, salt and vanilla extract, stirring until completely
incorporated. Stir in the flour, again stirring until it is well
mixed. The batter will be very stiff.
Crack the eggs into a small bowl, and beat them well with a
fork or whisk. Add the eggs to the batter and stir with a spoon
until they are completely incorporated. Stir in the chocolate
chips and the nuts (if using).
Spread the batter in the greased pan -- it will be stiff and
sticky. You may have to spread it to the edges of the pan with
the back of a spoon, but don't worry about getting it exactly
even, as the batter will spread as it bakes.
Bake until the top begins to get golden brown and the blondies
just begin to pull away from the sides of the pan, about 20 to
25 minutes. Do not overbake! Cool for at least 20 minutes,
and cut into small squares. Store in an airtight container or
cover well with plastic wrap. These bars freeze very well and
improve in flavor after the first day.