Preheat oven to 400°F (200°C). Grease a 9-inch springform pan.
Whisk the 2 cups of flour with the sugar, baking powder, and salt. Set aside.
In a large bowl, whisk together the egg, milk, yogurt, and oil. Gradually add the flour mixture, mixing just until combined.
Set aside about 1/4 cup of blueberries. Toss the remaining blueberries with 1 tablespoon of flour, and gently fold them into the batter.
Transfer the batter to the prepared pan, and spread evenly. Sprinkle the reserved blueberries over the top of the batter.
Combine the hazelnuts, turbinado sugar, and cinnamon. Sprinkle over the top of the batter.
Bake 28 to 32 minutes, or until a pick inserted into the center comes out clean.
Cool in the pan for about 15 minutes before removing the sides of the pan.
Notes
Using plain yogurt: Plain yogurt works well here, too. Add about 1/2 teaspoon vanilla extract if you’d like a little extra vanilla flavor.
Frozen blueberries: Frozen blueberries can be used straight from the freezer. Don’t thaw them first, or they may add excess moisture and streak the batter.
Pan options: A springform pan makes the cake easier to remove neatly, but a standard 9-inch round cake pan will work as well.
Storage: Cover tightly and store at room temperature for up to 3 days.
Freezing: Wrap the cooled cake tightly and freeze for up to 3 months. Thaw at room temperature before serving.