Grease and flour a deep 8-inch (20cm) diameter round baking pan. Arrange sliced nectarines in a circle on the outer perimeter of pan. Place ½ cup (60g) blueberries in the middle.

In a medium sized bowl, combine flour, baking powder, and baking soda. Set aside.

In a mixing bowl, cream butter and sugar till light and fluffy, about 3 minutes. Add vanilla and then eggs, one at a time, beating after each addition.

Beat in dry mixture and sour cream alternately on low to medium speed until just combined. Fold in the rest of the blueberries and pour batter into prepared pan.

Let cake stand in pan for 5 minutes. Invert cake onto plate keeping plate and pan firmly pressed together. Replace any fruit stuck to the bottom of the pan.

Serve cake at room temperature.