Preheat oven to 350°F (180°C)
Grease and flour a 10¼" (26 cm) springform pan. (Use parchment paper to line the base if desired)
Sift together the flour, baking powder and salt, then mix well.
Beat the butter and sugar together until smooth.
Add the eggs one by one, beating continuously.
Beat in the lemon juice and lemon zest and then gradually add the flour. Mix until smooth, then pour and spread evenly in the springform pan.
Arrange the nectarine slices on the surface of the sponge mixture, pressing lightly to make them stick in place.
Mix together the cinnamon, nutmeg and 4 tbsp (45 ml) sugar and sprinkle lightly over the nectarine topping.
Bake for approximately one hour, until a wooden pick comes out clean when inserted into the middle of the cake.