- 2 tablespoons canola oil, plus more for pan
- 4 cups all-purpose flour, divided, plus more for pan
- 1/2 cup sugar
- 2 1/2 teaspoons baking powder
- 1/2 teaspoon salt
- 1 large egg
- 1/2 cup milk
- 2 teaspoons vanilla extract
- 1 cup packed light-brown sugar
- 1 1/2 teaspoons ground cinnamon
- 1 cup unsalted butter, melted and cooled, room temperature
- Confectioners sugar, for dusting
- Preheat oven to 325 degrees F.
- Brush a 9×13-inch baking dish with canola oil, then line with parchment paper. Secure parchment paper to the baking dish using binder clips, then brush with oil and dust with flour. Discard excess flour. Set aside.
- In a medium bowl, mix 1 1/2 cups of the flour, sugar, baking powder and salt. Set aside.
- In a second medium bowl, whisk the egg, milk, canola oil and vanilla until well combined. Using a flexible rubber spatula, fold the flour mixture into the egg mixture.
- Spread the cake batter evenly in the prepared baking dish. Set aside.
- In a third medium bowl, combine the remaining 2 1/2 cups of flour, brown sugar and cinnamon. Pour the melted butter over the four mixture. Using a flexible rubber spatula, toss until crumbs form. Sprinkle the crumbs evenly over the cake batter.
- Bake the pan for 10 minutes, then rotate the pan. Bake until a cake tester comes out clean, about another 20 minutes.
- Transfer the cake to a wire rack. Allow to cool completely, then dust with confectioners sugar. Cut the cake into 3-inch squares.
Store cake squares in an airtight container for up to 48 hours.