Resift the flour into a mixing bowl with the baking powder and salt; set aside. In a separate bowl, beat egg with honey. Add milk and melted butter. Stir mixture into the flour mixture, stirring just until dry ingredients are moistened. Stir in the chopped dates and all but the reserved 2 tablespoons of the chopped walnuts.
Make topping. Combine brown sugar, flour, and cinnamon. Cut 1 tablespoon butter into the flour mixture to make a crumbly mixture; add reserved 2 tablespoons of chopped walnuts.
Spoon muffin batter evenly into 12 greased and floured muffin cups (about 2 1/2-inch muffin cups). Sprinkle Cinnamon Streusel Topping over each muffin.
Bake muffins at 375° for 18 to 22 minutes, or until nicely browned. Cool for 2 or 3 minutes in pan; turn out, loosening with knife or spatula if necessary.
Serve warm. Makes 12 muffins.