Preheat the oven to 180°C (356°F). Line an 8-inch round pan with parchment paper.
Sift together flour, baking powder, and salt. Set aside.
Separate the egg whites and yolks into two large bowls.
With an electric mixer, beat egg whites until lightly stiff.
Gradually add 1/4 cup of sugar to the egg whites and beat for 2-3 minutes until stiff peaks form. Set aside.
Beat egg yolks for 2-3 minutes until light and creamy.
Add the remaining 3/4 cup sugar, water, and vanilla extract to the yolks, and beat for 1 minute.
Gently fold the sifted flour mixture into the yolk mixture in two batches, being careful not to overmix.
Fold in the beaten egg whites, maintaining as much air as possible.
Add melted butter and gently fold into the batter. (It's okay if the butter is not fully incorporated.)
Pour the batter into the prepared baking pan and bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.
Cool the cake completely on a wire rack.
For the Topping: Whip the cream to the desired consistency, then add icing sugar and vanilla and mix well.
Place the cooled cake on a cake plate. Spread the strawberry jam over the cake, then top with whipped cream.
Decorate with fresh strawberries.
Slice and enjoy!