1. In a 2- to 3-quart pan over low heat, frequently stir butter and brown sugar until melted and smooth. Remove from heat and stir in eggs, vanilla, and flour until well blended.
2. Spread batter evenly in a buttered and floured 8-inch square baking pan. Sprinkle pecans evenly over batter.
3. Bake in a 350° oven until edges feel firm to touch and begin to turn a shade darker, 25 to 30 minutes.
4. Run a knife between pan rim and blondie. Let cool in pan on a rack, about 1 hour. Cut into 9 or 16 squares.
Note: Nutritional analysis is per small blondie.