Preheat oven to 350. Mix flour, baking powder, salt and baking soda in medium bowl.
Melt butter in large saucepan over low heat. Remove saucepan from heat. Add sugar and whisk to blend. Whisk in eggs and vanilla extract. Gradually stir in flour mixture (batter will be thick). Spread batter in jelly-roll sized pan. Sprinkle with chocolate chips and pecans.
Bake blondies until tester inserted into center comes out with moist crumbs attached, about 25 minutes. Cool blondies in pan on rack. (Can be prepared 1 day ahead. Cover and let stand at room temperature.) Cut into squares and serve.
Bake
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