Prepare the Cake: Preheat your oven to 350°F (175°C) and grease and flour an 8-inch round cake pan. In a medium bowl, whisk together the flour, baking powder, and salt.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with milk. Mix until just combined.

Pour the batter into the prepared cake pan and smooth the top. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

Make the Crème Fraiche: In a large bowl, whisk the heavy cream until it begins to thicken. Add the powdered sugar and vanilla extract, then whisk until soft peaks form.

Assemble the Cake: Once the cake is completely cool, spread a layer of crème fraiche over the top and sides of the cake. Decorate with slices of strawberries, blueberries, kiwi, and raspberries, arranging them beautifully.