Line a 8x8 inch square baking pan with parchment paper, then wrap the outside completely with foil to prevent water from seeping in during the water bath. Preheat your oven to 325°F and position a rack in the lower third of the oven. Fill a larger roasting pan with about 1 inch of hot water and place it in the oven—this water bath will gently cook the delicate cake and keep it moist.
Combine the milk and unsalted butter in a microwave-safe bowl and heat in 30-second intervals, stirring between each, until the butter is fully melted—this should take about 1 minute total. Whisk in the cake flour until smooth with no lumps, then add the egg yolks one at a time, stirring gently after each addition to create a thick, pale base. Set this mixture aside while you prepare the meringue.
In a clean, dry bowl, beat the room-temperature egg whites on medium-high speed until foamy, then gradually add the 1/2 cup sugar while continuing to beat. Once the whites reach stiff, glossy peaks (this indicates a stable meringue that will add lift and structure to the cake), gently fold about 1/4 of this meringue into the yolk mixture to lighten it. Then carefully fold this yolk mixture back into the remaining meringue using a spatula, making broad strokes from bottom to top to preserve the airiness—I like to fold just until no white streaks remain to maintain maximum volume.
Pour the batter from Step 3 into the prepared pan and tap it twice on the counter to release any large air bubbles. Place the pan into the hot water bath in the oven and bake for 1 hour 30 minutes, until the top is lightly golden and a cake tester inserted near the center comes out with just a few moist crumbs. Let the cake cool in the pan for 15 minutes, then turn it out onto a wire rack to cool completely—this cooling step is crucial before moving to assembly.
While the cake bakes, hull and slice the fresh strawberries into 1/4-inch thick pieces, then toss them with 3 teaspoons of sugar in a bowl. Let them sit for 1 hour to release their juices—this creates a beautiful syrup for brushing on the cake layers. In a separate bowl, combine the 2 tablespoons sugar with 3 tablespoons of hot water and stir until dissolved, then add the 2 tablespoons of cold water and the strained liquid from the macerated strawberries. Set this glazing syrup aside to cool.
Bloom the gelatin by sprinkling it over 2 tablespoons of cold water and letting it sit for 2 minutes until spongy. Place the very cold heavy cream in a chilled bowl and begin whipping on medium-high speed until it reaches soft peaks. Microwave the bloomed gelatin for about 15 seconds until melted and clear, then slowly drizzle it into the whipping cream while continuing to beat. Add 2 tablespoons of sugar and the vanilla extract, then continue beating until stiff peaks form—I find that adding gelatin stabilizes the cream so it holds its shape beautifully for hours without weeping.
Once the cooled cake is completely cool, carefully slice it horizontally into two even layers using a long serrated knife or a cake leveler. Using a paring knife or vegetable peeler, gently scrape away the thin crispy top skin from each layer (this is a Japanese technique that gives a cleaner appearance). Brush both cut surfaces generously with the glazing syrup from Step 5 to add moisture and flavor. Spread a layer of the stabilized whipped cream from Step 6 on the bottom cake layer, arrange some of the macerated strawberries on top, then add another layer of cream. Place the top cake layer on the stack and spread the remaining cream over the top and sides, using an offset spatula or the back of a spoon for a light, rustic finish. Arrange whole or halved strawberries artfully on top of the cake for a stunning presentation.
