Instructions

1. Preheat oven to 400 F degrees and line standard muffin or cupcake pan with paper liners and set aside.
2. To make the crumb topping in a small bowl, whisk together flour, sugar and cinnamon, add melted butter and stir with a fork until crumbly. Refrigerate until ready to use.
3. To make the muffins in large bowl stir together flour, baking powder and salt and set aside.
4. In a medium bowl place 2/3 cup granulated sugar and lemon zest and rub for a minute. Add eggs and whisk together eggs and lemon-sugar until combined. Whisk in yogurt, oil, lemon juice and vanilla extract (mixture should be pale and yellow)
5. Fold wet ingredients into dry ingredients and whisk everything together.
6. Reserve ½ cup of blueberries for topping. Place remaining blueberries in a small bowl. Dust blueberries with 1 tablespoon flour and toss them until all blueberries are coated with thin layer of flour and then fold them really gently in the batter.
7. Spoon batter into prepared muffin tins, filling maximum 2/3 of each cup and gently tap the pan on the work surface to set. Cover the batter with the remaining blueberries and then cover the blueberries generously with streusel topping.
8. Place them in the oven and bake at 400 F for 5 minutes, then REDUCE THE OVEN TEMPERATURE TO 375 F and bake 13-15 minutes or until the toothpick inserted in the center comes out clean.
9. Cool for 5 minutes in the pan then remove muffins and cool on a wire rack.