Gluten Free Strawberry Tiramisu

Preheat oven to 375°F (190°C). Line a 17 x 11.5-inch jelly roll pan with parchment paper.
Separate the egg yolks and whites. Place the egg whites in a clean metal or glass bowl. Beat on medium-low speed until frothy (about 1½ minutes). Add the cream of tartar and continue beating. Slowly sprinkle about ⅓ cup of the sugar into the egg whites while beating. Increase the speed and whip until stiff peaks form (about 6–7 minutes).
In a separate bowl, beat the egg yolks with the remaining sugar. Beat for 5–6 minutes, until pale and thick and the mixture forms ribbons. Sift ⅓ of the flour and cornstarch into the yolks and gently fold. Fold in ⅓ of the whipped egg whites. Repeat, alternating the flour and whites, until fully incorporated.
Spread evenly in your lined pan with a spatula. Bake for 13–14 minutes, until the sponge is puffed and golden.
Cool completely, then remove from the pan and peel off the parchment. Let the sponge dry out for 8–12 hours (overnight) before using.

Hull (i.e., remove the green tops) and thinly slice about 8 ounces of the strawberries. Set aside for the top of the tiramisu.
Hull and dice the remaining strawberries, then place them in a small saucepan with the sugar and water. Cook over medium heat, stirring, until the sugar dissolves. Cover the pan and simmer for 10 minutes, stirring occasionally.
Set a fine-mesh strainer over a small mixing bowl. Strain the strawberry sauce to remove the solids. Set the solids aside for later. Stir the orange liqueur into the strawberry syrup. Chill both in the refrigerator until ready to assemble.
In a medium bowl, combine the softened mascarpone cheese, cream, sugar, and vanilla extract. Beat with an electric mixer or stand mixer on medium-high speed for 1 to 1½ minutes, until smooth and thickened.
For assembly, cut the cake to fit a 9x9 pan (it is okay if it is in multiple pieces for one layer). Using a pastry brush, brush both sides of the cake with the strawberry syrup. Don’t soak it; we want flavor, not mush. Place it in the bottom of the pan. Top with half of the mascarpone mixture, then the strained strawberry pieces. Repeat with the next layer of cake and mascarpone filling. Top with the sliced strawberries.
Chill for four hours, or overnight, then slice and serve.