Blueberry Muffins

Mix your dry ingredients together: flour, baking powder, and salt.

In a bowl, whisk the egg with sugar until fluffy and pale, then add the butter, lemon zest, and vanilla extract, and stir to combine.

Gently fold in the flour mixture and sour cream, alternating between the two and starting and ending with flour.

Fold the berries into the batter—toss them lightly in flour first to prevent them from sinking.

Butter your muffin cups, divide the batter among them, and sprinkle brown sugar on top.