In a small bowl stir together the sugar, brown sugar, cinnamon, salt and butter. Add the flour and cornstarch, stir to make a soft dough, set aside.
In the bowl of a stand mixer add the flour, cornstarch, sugar, baking soda and salt. While the mixer is running add the butter mixing until the butter is cut in and the mixture resembles coarse meal with no uncombined lumps of butter.
Add the eggs, yolk, beer, olive oil and vanilla, beat until light and fluffy and well combined.
Line an 8x8 baking pan with parchment paper with the paper hanging over the sides. Pour batter into prepared pan in an even layer.
Crumble the topping and gently sprinkle it over the batter in an even layer. Bake for 35-40 minutes or until a toothpick inserted in the center comes out clean.
Allow to cool for ten minutes, remove from pan using the parchment overhang. Cut into squares, sprinkle with powdered sugar.