Make Topping: In a small bowl, add all topping ingredients and mix together by hand until fully incorporated and crumbly. Cover and chill until ready to use.
Prepare: Preheat oven to 350F, with baking rack on lower middle position. Grease a 10-inch Springform pan and set aside.
Mix: In the bowl of a stand mixer fitted with paddle attachment on medium-high speed, cream butter and sugar until fluffy and very pale yellow, about 3 minutes. Add cinnamon, nutmeg, vanilla, lemon juice, and eggs. Mix on medium speed just until smooth, about 1 minute. Add the yogurt and mix another minute.
More Mixing: Add flour, baking soda, salt, and flax meal if using. Mix on medium-low speed just until incorporated, scraping down sides as needed; do not over-mix (over-mixing causes a tougher texture.)
Fold, Transfer, and Bake: Remove bowl from stand mixer. Use rubber spatula to very gently fold blueberries into the batter. Transfer batter into greased Springform pan, spreading evenly. Sprinkle chilled topping evenly over batter. Place baking pan onto a large sheet pan and bake 45 minutes or until toothpick inserted in center comes out with a few tender crumbs attached.
Garnish: Sprinkle warm cake with Turbinado sugar on top. Allow cake to fully cool in pan on wire rack; gently remove sides of Springform pan to release cake.
Notes
Feel free to substitute half of the AP flour with whole wheat flour or white whole wheat flour.If you only have a 9 inch Springform pan, plan to adjust for a few extra minutes of bake time.If you want to keep berries from sinking to bottom, transfer half the batter without berries to the baking pan first, and fold berries into the remaining batter.Cake can be made the night before; allow it to cool in the pan at room temp, covered with foil, until ready to serve. To serve warm, reheat at 300F for about 12 minutes. If you enjoyed this recipe, please come back and give it a rating ♡