Blueberry Muffins with Lemon Streusel

For the muffins:
the oven to 400ºF. In a medium size bowl, add the flour, sugar, baking powder, salt and mix together. Add the egg, canola oil and milk. Mix together. Gently stir in the blueberries. Add the batter to a lined muffin tin and set aside for a moment.

For the streusel:
In a small bowl, add the brown sugar, lemon zest, flour, and butter. Cut (or smash) the butter into the mixture using a fork, until the mixture turns into small crumbles. Top the muffins with the streusel and bake until done (about 20 to 25 minutes). Let cool before serving.