1/4 cup finely chopped walnuts
2 tablespoons brown sugar
1 tablespoon chilled butter, cut into small pieces
To prepare streusel, combine walnuts, 2 tablespoons brown sugar, and chilled butter in a small bowl, stirring with a fork until crumbly. Sprinkle streusel evenly over batter. Bake at 350 for 20 minutes or until muffins spring back when touched lightly in center. Remove from pans immediately; place on a wire rack. Serve warm or at room temperature.