In a medium bowl, combine flour, sugars, cinnamon and salt. Cut in butter until mixture resembles wet sand; set aside.

Move oven rack to lower-middle position and preheat the oven to 350ºF. Spray an 8-inch round cake pan with non-stick baking spray and line the bottom of the pan with parchment paper.

In a small bowl, whisk together the flour and baking powder; set aside. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, sugar, salt, and lemon zest until light and fluffy, about 3 minutes. Scrape down the sides of the bowl. Add the vanilla and yogurt and beat until incorporated, about 30 seconds. Add the eggs one at a time and beat until combined. Scrape down the sides of the bowl and beat again. Reduce the speed to low and gradually add the flour mixture, mixing just until combined, about 20 seconds. Using a rubber spatula, stir the batter until no flour pockets remain, do not over mix. (The batter will be thick). Gently fold in the blueberries until evenly distributed.

Transfer the mixture to the prepared cake pan, gently pushing batter to the edges of the pan using an off-set spatula. Squeeze a handful of the streusel in your hand, breaking into large clumps and sprinkling over the batter.  Repeat with remaining streusel.  Bake for 55-60 minutes or until a toothpick inserted in the center comes out clean; streusel should be a deep golden brown.

Cool on a wire rack for 15-20 minutes.  Place a large upside-down plate over the cake pan and invert the plate to remove cake pan.  Remove the cake pan, then peel off the parchment .  Re-invert the cake onto a serving platter.  Serve slightly warm or at room temperature.

Cake can be kept covered at room temperature for up to two days or refrigerated for up to three days.  Chilled leftovers can be re-warmed in a 325ºF oven for 15-20 minutes. Enjoy!