Preheat oven to 350 degrees and lightly grease a 10 inch cake pan. A 9 inch springform pan, which usually has 3 inch sides, can be used. A 9 inch cake pan with 2 inch sides will be too small and overflow.

To make the streusel, combine all the streusel ingredients in a small bowl and stir to form a crumbly topping. Set aside.

For the cake, whisk together the melted butter, oil, sugar, and eggs in a medium bowl. Add the lemon zest, juice, and Greek yogurt and stir again to combine. In a separate bowl, stir together the flour, salt, baking soda, and baking powder. Add this to the liquid ingredients and gently stir to form a batter. Fold in the blueberries and transfer to the prepared cake pan, then top evenly with the streusel mixture.

Bake for about 45 minutes (a 9 inch pan may take an hour or longer) or until a toothpick inserted comes out clean (make sure to get underneath the streusel) and the top of the cake springs back when lightly touched. To make the icing, stir the lemon juice and powdered sugar together to form a thick glaze and drizzle over the cake.