Step 1

Preheat oven to 350 degrees F. Liberally grease a 9x13" rectangular baking pan with cooking spray and set aside.

Step 2

In a large bowl, combine all of the cake ingredients with an electric mixer on low speed for about 30 seconds, until just combined. Scrape down the bowl and beat for an additional 2 minutes or until completely combined and smooth. Pour into the pan and smooth out the top.

Step 3

Bake for approx. 25-35 minutes or until a toothpick inserted near the center comes out clean or with moist, not wet, crumbs. Cool completely.

Step 4

To make the frosting: In a medium saucepan, mix the flour and the milk with a wire whisk until smooth. Cook over medium heat until mixture becomes very thick, stirring constantly to prevent burning. Remove from the heat and cool for 10-15 minutes.

Step 5

Meanwhile, in a large bowl, beat the sugar and butter together until light and fluffy. Add in the flour mixture gradually, mixing well after each addition. Beat in the vanilla extract until smooth.

Step 6

Frost the cake evenly with the frosting. Top with white chocolate curls or shavings, if using. Cover cake and store in the fridge to set for about 2 hours before cutting into slices.