Heat oven to 350 degrees F. Generously grease 6 jumbo size muffin pans; set aside.
In bowl of electric mixer, cream butter and sugar until light and fluffy. Beat in egg, milk, and lemon peel. Stir in flour, baking powder, and salt just until blended. (Batter will be lumpy) Fold in blueberries just until mixed in. Spoon evenly into prepared muffin pan.
For topping: In a small bowl, mix together streusel topping ingredients until well blended. Sprinkle evenly over the top of the 6 muffins.
Bake muffins for 23-26 minutes or until a tester inserted in the middle of a muffin comes out clean. Remove from oven and let muffin tin rest on a wire rack for 5 minutes. Run a knife around the edge of each muffin and remove from tin to wire rack. Serve muffins warm with lots of butter!
Recipe by The Culinary Cellar at https://theculinarycellar.com/its-a-muffin-morning/