Step 1Heat the oven to 350 degrees. Spray a 9- by 2-inch round cake pan with pan coating and line it with parchment paper.Cut the nectarines in half and remove the pits. Cut the halves into 1/8-inch-thick slices.
Step 2Sift together the flour, sugar, baking soda, baking powder, salt and cinnamon.
Step 3In a separate bowl, combine the eggs, milk, olive and canola oils. Whisk to blend. Slowly add the egg mixture to the flour mixture, whisking to make a smooth batter.
Step 4Pour the batter into the prepared pan. Starting on the outside of the cake pan, arrange nectarine slices in an overlapping circle on top of the batter, making smaller concentric circles of slices until the surface is covered. Gently press down the slices, just so they are coated with batter. The batter will fill the pan to the rim.
Step 5Bake for about 1 hour and 10 to 15 minutes, rotating the pan halfway through, until the top is golden brown and a wooden skewer inserted in the center comes out with moist crumbs. The cake will puff up while baking and deflate slightly as it cools.
Step 1Place the sugar in a small saucepan. Add the corn syrup and 5 tablespoons of water to give the mixture the consistency of wet sand.
Step 2Cook over medium-high heat until the sugar syrup begins to caramelize, about 5 to 8 minutes. Once a dark honey color is reached, reduce the heat to low and add half the diced nectarines. Cook the fruit in the caramel for 3 to 4 minutes, until the juices are released and the sauce becomes more liquid.
Step 3Remove the nectarines from the caramel sauce with a slotted spoon and add them to the bowl with the remaining uncooked fruit. Combine the cornstarch and the remaining water in a small bowl and stir into the caramel sauce in the pan. Bring the sauce back to a boil and simmer until slightly thickened and the starch flavor is cooked out, about 2 minutes.
Step 4Add all the fruit to the sauce and stir over low heat about 30 seconds. Remove from the heat and set aside until ready to serve.
Step 5When the cake is done, place it on a cooling rack for 10 minutes. Run a knife around the edge of the cake and invert it onto a plate. Remove the parchment paper and turn the cake over again onto a serving platter.
Step 6Serve slices of warm cake with a spoonful of room-temperature compote and vanilla bean ice cream.