Step 1

Preheat oven to 350 degrees F.

Step 2

Cream together the butter and sugar until light and fluffy.

Step 3

Add the eggs and vanilla extract. Add the eggs one at a time, beating well after each addition.

Step 4

Sift together the flour and baking powder.

Step 5

Add dry ingredients alternately with the milk

Step 6

Always begin and end with an addition of dry ingredients. As a general rule, add the flour mixture in 3 divisions and the milk in two.

Step 7

Quickly fold in the blueberries and lemon zest.

Step 8

Spoon batter evenly into paper lined muffin tins, filling only about 3/4 full.

Step 9

In a large bowl toss together the flour, baking powder, oats, and brown sugar.

Step 10

Using your hands, rub the cold butter thoroughly through the dry ingredients.

Step 11

Sprinkle the crumble mixture evenly over the tops of the muffins.

Step 12

Bake in a preheated 350 degree F oven for about 20-25 minutes or until a wooden toothpick or skewer inserted into the center of a muffin comes out clean. The baking time may vary depending on whether fresh or frozen berries are used.