Spray a 9-inch springform pan with cooking spray and set aside.
In a small bowl combine the flour, baking powder, and ¼ tsp. salt.
In the bowl of a mixer, combine the butter and the sugar. Beat until creamy.
Add the eggs, one at a time, beating until fully incorporated. Add the vanilla and rum, if using.
Add the flour mixture and mix just until the flour is fully incorporated.
Spoon batter into prepared pan (it will be thick!) spreading evenly. Lay the nectarine slices side by side along the edge of the pan in a decorative pattern.
Sprinkle the top of the cake with the brown sugar and crystallized ginger. Bake for 35 - 40 minutes or until a tester inserted into the center of the cake comes out clean.
Let cool and brush the fruit with the apricot jam if desired.
FRUIT: When choosing stone fruit for this recipe, look for fruit that is not overly ripe since the fruit will disentegrate when it's baked. There is no need to peel the fruit - just wash and slice!
SUGAR - for the topping, I used Raw sugar. Turbinado and Demerara are also considered raw sugars so all three can be used interchangeably in this recipe.
CRYSTALIZED OR CANDIED GINGER: You can omit this from the recipe but I love the little bit of spicy heat it adds to the cake.
DARK RUM: You can definitely leave this out, but if you happen to have any on hand, do try adding it to the cake - the subtle caramel notes it adds really complements the fruit!
APRICOT JAM: Again this is optional, but it makes this humble cake look a little prettier!
STORAGE: This cake is best eaten within a day of baking. Cover it well with plastic wrap (or under a cake dome) and store at room temperature. For longer storage, wrap well in plastic wrap and store in the refrigerator. Let come to room temperature before serving.
SERVING SUGGESTIONS: I love this cake just as it is, but a little bit of softly whipped, lightly sweetened whipped cream goes really well.