Whisk together water and cornstarch in a medium saucepan until it is fully mixed and there are no lumps.

Add in remaining ingredients.

Cook over medium to medium high heat and bring to a boil.

Let boil for 30-60 seconds (no more than a minute). Do not over boil or the cornstarch can lose its thickening ability. It should turn from an opaque milky pink color to deeper red and more transparent.

Once it turns red, immediately turn down the heat to medium low and let simmer for 8-10 minutes. It should be thick enough to thickly coat a spatula and not drip off. It will thicken more as it cools.

Remove from heat and let cool completely before using. It can be made a day ahead and stored in the refrigerator until ready to use.

Prepare two 8 inch baking pans with baking spray lined with parchment paper.

Preheat oven to 350 ℉.

In a medium bowl, whisk together flour, cornstarch, salt, and baking powder. Set aside.

In the bowl of a standing mixer with paddle attachment, or a large both with a hand held mixer, cream butter and sugar for 3-4 minutes. It should be light and fluffy.

Slowly add the egg whites, one at a time and mix fully after each addition, scraping down the sides of the bowl with a spatula as necessary.

Mix in oil and vanilla extract until incorporated.

Alternate adding the flour mixture and the whole milk, starting and ending with the dry ingredients (three additions of flour and two of milk).

Do not over mix, you want to stop as soon as all the flour is incorporated.

Divide the cake batter evenly between the prepared cake pans, smoothing the tops with a spatula.

Bake in preheated oven 25-30 minutes, or until you can poke the middle of the cakes with a toothpick and it comes out mostly clean or with only a few crumbs on it.

Let cool in the pan for 10 minutes and then let cool completely on a wire rack before frosting.

In a medium saucepan mix milk, sugar, and flour over medium heat, about 2-4 minutes until the mixture starts to bubble and thicken. You’re looking for a pudding like consistency.

In the bowl of standing mixer or using a large bowl with a hand held mixer, beat the softened butter 3-5 minutes until pale yellow.

Slowly add the cooled flour mixture 1-2 tablespoons at time, making sure it is fully incorporated before adding more.

Once you’d added all the flour roux, turn up the speed and mix another 3-5 minutes until light and fluffy.

Add vanilla, salt, and any other flavorings and remix until combined.

Fill in the middle with the strawberry filling and add the second layer of cake.

Frost the top and sides of the cake with the remainder of frosting. Add any optional decorations in top such as the more strawberry topping, fresh strawberries, or more piped frosting.

Enjoy!