In a bowl, sift the gluten-free flour, cornstarch, baking powder, and salt together.
2 Cups 1:1 Gluten-free Flour, 2 Tablespoons Cornstarch, 2 ¼ Teaspoons Baking Powder, ½ Teaspoon Salt
Separate the egg yolks and whites into two separate bowls.
4 Large Eggs
Add 1 cup of the sugar to the bowl with the egg yolks along with the butter and cream them together until the color is very pale yellow and the mixture is light and fluffy.
1 ¼ Cups Sugar, ¼ Cup Butter
In the bowl with the egg whites, add the remaining ¼ cup of sugar and whip them until stiff peaks have formed.
1 ¼ Cups Sugar
To the bowl of the egg yolk, mix in the bowl of dry ingredients. The mixture will look like course sand at this point.
Once you have a coarse sand like texture, add the milk and vanilla and bring the batter together until it's smooth.
1 Cup Whole Milk, 2 Teaspoons Vanilla.
To the batter, CAREFULLY fold in the egg whites. The batter will start a little stiff but it will loosen and become fluffy once you add the eggs. DO NOT overmix. You want to just fold the egg whites until incorporated.
Transfer the cake batter to a greased 9x13 baking pan.
Bake in the preheated oven for 35-45 minutes or until a toothpick inserted comes out clean.
Allow the cake to cool.
For the milk soak.
In a bowl, combine the whole milk, the evaporated milk, and the sweetened condensed milk.
Using a fork, poke holes into the top of the cake in the pan,
Slowly pour the milk mixture over the cake in the pan, making sure to cover all the surface area and around the edges of the cake.
Cover and place the cake in the fridge for at least an hour or overnight.
Top and serve.
Sprinkle the unflavored gelatin into a small microwave safe bowl.
1 Package Unflavored Gelatin
Add the cold water and whisk until all the gelatin is absorbed, and let it rest for about 5 minutes.
3 Tablespoons Cold Water
In a chilled bowl, whip the heavy cream, powdered sugar, and vanilla together until it reaches soft peaks.
2 Cups Heavy Whipping Cream, 1 Teaspoon Vanilla, 1 Cup Powdered Sugar
Check your gelatin and see if it has solidified. If it has, microwave the gelatin for about 5-10 seconds until it is a liquid again, but not very hot.
With the mixer on low, drizzle the gelatin into the whipped cream. Slowly increase the speed on the mixer to medium and then high, and continue mixing until you've reached stiff peaks.
Use the stabilized whipped cream to frost the top of the cake.
Dust the cinnamon over the top, slice, and enjoy!
1 Teaspoon Cinnamon
Notes
Measure the gluten-free flour by weight. - When it comes to baking, if you want the same results every time, weigh your ingredients.
Use room temperature ingredients. - This means your eggs, butter, and milk should all be at room temperature.
Really cream the egg yolks. - The egg yolk mixture should look pale yellow and light and fluffy when fully creamed them.
Once you add the flour to the egg yolk, the mixture will look crumbly, and you will think you've done something wrong. Don't worry. We use a little reverse creaming method to help add more air to our cake. Once you add the milk and vanilla, it will come together in a smooth batter.
Bring the egg whites to stiff peaks. - The air in the egg whites helps with the final texture of the cake. Make sure you are bringing your egg whiles fully to stiff peaks.
GENTLY FOLD the egg whites into the batter. - The batter will start stiff but lighten as you fold the egg whites into it. Be careful not to over-mix the egg whites into the batter. You want to leave as much air as possible and not deflate the egg whites.
Do not overbake. - This cake takes about 35-45 minutes to bake at 350 degrees. My oven takes right about 40 minutes on average. Watch your cake in the oven and start checking it at about 35 minutes of baking, depending on your oven.
Let the tres leches mixture soak on the cake for at least an hour, but it's even better when left overnight in the fridge.
I tend to reserve the whipped cream topping and add it on top right before serving, so it's fresh.