01 - Preheat the oven to 350°F (180°C). Grease and line two 8-inch (20 cm) round cake pans with parchment paper.
02 - In a large mixing bowl, combine eggs, granulated sugar, and salt. Beat with an electric mixer on high speed for 5 to 7 minutes, until pale, thick, and tripled in volume.
03 - Gently fold in all-purpose flour and vanilla extract using a spatula, taking care not to deflate the mixture.
04 - Divide the batter equally between the prepared cake pans. Bake for 20 to 25 minutes or until golden and springy to the touch.
05 - Remove pans from the oven and let cool for 10 minutes. Turn out cakes onto a wire rack to cool completely.
06 - While cakes are cooling, whip heavy cream, powdered sugar, and vanilla extract in a mixing bowl until soft peaks form.
07 - If using, spread a thin layer of strawberry jam over one cooled sponge. Spread half of the whipped cream on this layer and top with half of the sliced strawberries.
08 - Place the second sponge cake layer on top of strawberries. Spread the remaining whipped cream over the top and arrange the rest of the strawberries.
09 - Garnish with fresh mint leaves if desired. Chill the assembled cake for at least 30 minutes before slicing.