Preheat the oven to 350° F (convection).

Spray a 9 by 9-inch baking dish or round springform pan with oil and set aside.

In a medium mixing bowl whisk together the flour, baking powder, salt, ground cinnamon and lemon zest. Set aside.

Beat together the butter and sugar in a large mixing bowl on medium (5 or 6) speed until light and fluffy, approximately 2-3 minutes.

Mix in the egg and vanilla extract.

Add half the flour mixture and beat on low speed just until incorporated and then add half of the milk and beat until incorporated. Repeat, alternating flour and milk until fully incorporated.

Rinse blueberries and toss in a bowl with a small amount of flour until coated. Gently fold the blueberries into the batter, then pour into the prepared baking pan. Set aside while you make the topping.

TOPPING:

In a small bowl whisk together the sugar, flour, spices and baking powder.

Add the cold butter and cut into the dry ingredients using a fork or pastry cutter to combine. It will make a crumbly mixture that is not uniform.

Sprinkle the mixture across the top of the cake batter.

Bake on the middle rack of the oven for 45-55 minutes (depending on the pan) or until golden in color, them middle isn't sunken in and a toothpick inserted into the center comes out with some crumbs attached, not wet.

Cool for at least 10 minutes before serving.