To make a sponge cake, preheat the oven to 305°F (150°C). Sift cake flour with a flour sifter twice in a large mixing bowl. Butter and dust a 7-inch (18 cm) pan with flour, and remove the excess flour. Or line the bottom and sides of the baking pan with a parchment paper circle and strips.

Place egg whites in a large bowl or the bowl of a stand mixer with the whisk attachment and beat on low-medium speed until frothy. Add 1/3 of sugar and continue whisking on low speed. Add another 1/3 of the remaining sugar, and beat the egg whites until soft peaks. Avoid stiff peaks and glossy meringue.

Add egg yolks and gently mix with a hand whisk with circular movements. Avoid any up-and-down whisking motions.

Sift 1/2 of the flour over the bowl and carefully mix with a hand whisk without whisking. Add the remaining flour and mix until the flour is invisible.

Place oil and milk in a small microwave-safe bowl and warm them up in the microwave for 20 seconds. Add the warm milk and oil mixture to the main preparation. Gently mix by scooping the batter up from the bottom with a spatula until you obtain a uniform batter.

Pour batter into the prepared pan and tap it on the table a couple of times. Stir the batter with a bamboo screw with circular movements. These tricks help eliminate air bubbles and create an ideal texture for the cake.

Bake the cake for 60 minutes. Remove the baking pan from the oven and tap the mold on the table. Let the cake cool in the pan for 5-10 minutes.

Turn the pan upside down on a wire rack and let the cake cool for 5 minutes. Then turn it over, and while the cake is warm, scrape the crust from the top of the cake with a thin sharp knife. Don't trim the cake yet; just remove the top crust. Let the cake cool down completely.

To make sugar syrup, pour water and sugar into a small saucepan and bring to a boil. Out of the heat, add Kirsch, and let it cool.

To make fresh whipped cream, pour 2/3 cup + 3 tablespoons (200 g) of chilled heavy cream and icing sugar into a cold bowl and whip cream with a hand whisk until soft-medium peaks.

Pro tip: Consult a Japanese strawberry shortcake for how to make fresh whipped cream. It is different from the Westen-style homemade whipped cream. If desired, opt for stabilized whipped cream. 

To make strawberry cake filling, wash and pat dry strawberries. Hull and cut strawberries into halves, then quarters. Mash using a potato masher or a fork. Combine mashed strawberries, sugar, and lemon juice in a saucepan. Cook over medium heat for 2-3 minutes. Remove from heat and allow to cool completely. The sauce will thicken as it cools.

To assemble the cake, measure the height of the cake. You will need to get four 0.4 inches (1 cm) thick cake layers. If the cake size allows you to cut the bottom of the cake, do this. Otherwise, leave the bottom crust. Use a serrated knife or cake leveler to slice the cake into thin layers 1 cm thick. Adjust a mousse cake mold to 6.4 inches (16 cm) and trim each layer to fit. 

Place the first layer on a turntable. Soak it with syrup using a pastry brush. Spread 1/4 of the cream evenly with a bent spatula. Then, using a pastry bag or spoon, add 1/3 of the strawberry filling on top of the cream. Make sure to leave a 1/2 inch (1.5 cm) gap from the edge. 

Place the second cake layer and repeat the above procedure. Finish the cake with the third cake disk and soak it. Crumb coat the top and sides of the cake with a thin layer of cream. Whisk 2/3 cup (155 g) of the cold heavy cream with a hand whisk until soft peaks and cover the entire cake.

Decorate the cake with an angled spatula: read a Wilton tutorial on how to make spatula icing. Arrange a few fresh strawberries on top.