Preheat to 350F. Grease 13x9x2" baking pan.
In large microwave safe bowl place butter.
Microwave on HIGH (100%) 2-2 1/2 min. or until melted.
Stir in sugar and vanilla.
Add eggs, one at a time,
beating well with spoon after each addition.
Add cocoa; beat until well blended.
Add flour, baking powder and salt; beat well.
Stir in nuts, if desired.
Pour batter into prepared pan.
Bake 30-35 min or until brownies begin to pull away
from sides of pan. Cool. Cut into bars.
About 36 brownies.