Method
Make the Cake
- Preheat oven to 325°F. Grease a 9x13 inch baking pan with cooking spray, add a small handful of flour, tilt to coat, and discard the excess
- Melt the butter and set aside to cool
- In a large bowl whisk together the flour, granulated sugar, baking powder, and salt. In a separate bowl whisk together the egg, milk, vanilla, and canola oil
- Fold the dry ingredients into the wet ingredients just until a lumpy batter forms. Do not overmix or the cake will be tough
- Spread the batter as evenly as possible in the prepared pan, making sure it reaches all the edges. The consistency is thick and stretchy — just do your best
Make the Crumb Topping
- In a bowl stir together the flour, brown sugar, and cinnamon. No need to break up small clumps of brown sugar unless they are larger than a pea
- Pour the melted butter over the mixture and fold with a rubber spatula until large crumbs form. Break up any overly large pieces with your hands if needed
- Sprinkle the crumbs evenly over the cake batter, covering it completely with no bare patches
Bake and Finish
- Bake for 10 minutes, rotate the pan, then bake for another 10 minutes. Test with a toothpick in the center — if it comes out clean the cake is done. If not, bake for another 3–5 minutes watching closely
- Remove from the oven and cool completely on a wire rack or trivet
- Once fully cooled, dust generously with powdered sugar and slice into squares with a sharp knife
Notes
Do not overmix the cake batter — fold just until combined for the most tender crumb. For a slightly more moist cake substitute buttermilk for the regular milk. The crumb topping should form large chunky crumbs; if it seems too fine work it briefly with your hands. Store covered at room temperature for up to 3 days