Impress your guests with this summery dessert. Serve with a dollop of fresh whipped cream.
Preheat oven to 350°F with rack in middle. Lightly butter 9- springform pan.
Whisk together flour, baking powder, and salt.
Beat butter and ¾ cup sugar with an electric mixer until pale and fluffy. Add eggs 1 at a time, beating well after each addition, then beat in extracts. At low speed, mix in a flour mixture until just combined.
Spread batter evenly in pan, then scatter nectarines over top. Stir together nutmeg and remaining ½ tablespoon sugar and sprinkle over top. Back until cake is golden-brown and top is firm but tender when lightly touched (cake will rise over fruit), 45-50 minutes. Cool in pan 10 minutes. Remove side of pan and cool to warm.