Start by preheating an oven to 180c (350f) and prepare a 9-inch springform pan with parchment paper.
Make the crumble topping: In a medium mixing bowl, add the flour, kosher salt, and brown sugar. Mix with a spoon until the mixture is well combined.
Add the melted butter and mix until well combined. Place in the fridge while you make the cake.
Into a large mixing bowl, add the cooled melted butter, eggs, granulated sugar, vanilla extract, lemon zest, lemon juice, buttermilk, kosher salt, and Greek yogurt, and mix with a whisk until well combined.
Add the frozen or fresh blueberries into the cake batter, and fold it lightly with a rubber spatula until combined.
Pour the cake batter into a 9 inch springform pan lined with parchment paper and smooth it out using an offset spatula.
Top the cake with the streusel topping and press the streusel topping onto the cake batter so it sticks and does not fall off while baking. Top it with more blueberries and press them into the cake batter as well.
Bake in a 180c (350f) preheated oven for about 60-70 minutes or until a toothpick inserted into the cake comes out clean, usually with a few moist crumbs.
Remove the cake from the oven and let it cool for 30 minutes before you release it from the pan so it will not crumble up and stay stable.
Make a simple glaze: In a small mixing bowl, add the powder sugar, milk, and vanilla. Mix with a spoon until the mixture is well combined and until the glaze is smooth and silky.
Drizzle as much glaze as you like on to of the cake, serve, and enjoy.
Notes
Push the streusel topping onto the cake lightly so it would stick to the top of the cake while baking and not fall off.
Use fresh, ripe blueberries. Opt for plump, juicy blueberries that are in season for maximum flavor.
Use room temperature ingredients. It is important that you use room-temperature ingredients like eggs and milk. This step ensures that your mixture mixes into a homogenous mixture and bakes perfectly. you don’t want to place cold batter into the oven.
Don’t overmix the batter, you don’t want to develop the gluten in the flour. This step ensures you have moist cake and not dense and dry cake.
Measure your flour correctly! When measuring your flour, avoid scooping it with a measuring cup. Instead, stir the flour with a spoon to create as many air pockets as possible, and spoon it into your measuring cup. Finally, level it with a back of a knife.
Add some of your favorite add-ins! Make this recipe your own and add your favorite cake add-ins: chocolate chips, chopped walnuts, chopped pecans, chocolate chunks, banana slices, chopped fruit, and more! Be creative!
Be patient! I know it's extremely tempting to eat this cake as it is pulled out of the oven, but let this cake cool for at least 1 hour so it will be firmer and won't crumble up.