In a medium bowl, stir together flour, baking powder and salt.
Using an electric mixer, cream the butter and sugar until light and fluffy. Beat in eggs, one at a time, until smooth. Stir in extracts.
On low speed, stir in half the flour mixture, then half of the milk. Repeat. Mix just until incorporated, no more.
By hand, fold in the lemon zest and blueberries.
Portion into the prepared muffin tin. Evenly distribute the streusel topping over the muffins.
Bake for 20-25 minutes until a toothpick tests clean. Cool in the pan a few minutes, then gently remove to a cooling rack.