Preheat the over to 350 degrees F (180 degrees C, or gas mark 4) and line a 12-cup muffin pan with paper liners.

To make the muffins: In a large bowl, combine the flour, starch, cinnamon, baking powder, and salt. In a separate small bowl or mixing cup, combine the eggs, honey, and vanilla. Add the wet mixture to the dry ingredients, mixing just enough to combine, and then gently fold in the blueberries.

To make the topping: In a small bowl, use your fingers to crumble together the topping ingredients.

Divide the muffin batter evenly among the 12 muffin cups. Top each with crumb topping. Bake for 35 to 40 minutes or until a toothpick inserted into the center comes out clean. As soon as the muffins are cool enough to handle, transfer them to a rack and allow to cool before serving.