Preheat the oven to 170 C (325 F). Grease a 9 inch round springform tin and line the bottom and sides with baking paper.
To make the cake, using an electric mixer, beat the flour, sugar, baking powder, baking soda, salt and butter on a low speed until the mixture comes together and resembles a crumble.
Meanwhile, combine the Greek yogurt, egg, egg yolk and vanilla in a small bowl. Add it into the crumble mixture in 3 batches, beating well after each addition.
Pour the cake batter into the springform tin and spread out evenly with the back of a spoon.
To make the filling, hull and quarter the strawberries. Toss them with the sugar and cornstarch and scatter evenly over the cake batter in the tin.
To make the crumb topping, combine all the ingredients with a fork in a medium bowl until all the flour is incorporated. Crumble the mixture in an even layer over the strawberries.
Bake the cake for 1 hour. Allow to cool before removing from the tin and cutting. Serves 8 - 10.
Recipe by Butter Baking at https://www.butterbaking.com/2012/04/21/strawberry-crumb-cake/