Preheat oven to 350°F (175°C).

Grease and flour an 8 1/2-inch springform pan.

In a large bowl, beat eggs and 3/4 cup sugar until light and fluffy using an electric mixer.

Sift flour, baking powder, and salt over the egg mixture.

Gently fold the dry ingredients into the wet ingredients until just combined.

Pour the batter into the prepared springform pan.

Bake in the preheated oven for 25 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for a few minutes before transferring it to a wire rack to cool completely.

Once the cake is cool, use a serrated knife to slice it horizontally into two layers.

In a chilled bowl, whip the heavy cream with the remaining sugar and vanilla extract until stiff peaks form.

Gently fold 1/2 of the mixed berries into half of the whipped cream.

Spread the berry cream mixture evenly over the bottom cake layer.

Top with the remaining cake layer.

Spread the remaining whipped cream over the top and sides of the cake.

Arrange the remaining fresh berries on top of the cake for decoration.

Serve immediately or chill for later.