Preheat oven to 325°F Lightly spray 9 inch springform pan with oil and set side.
Whisk flours with cinnamon, baking soda, nutmeg and salt in a medium bowl.
Whisk egg with granulated sugar and 2/3 cup oil in a large bowl. Stir flour mixture into egg mixture. Stir in chopped pecans and grated apples.
Scrape into prepared pan and smooth top. Arrange overlapping apple slices around edge of cake. Arrange pecan halves in one layer in centre.
Make glaze by stirring brown sugar, 2 tsp olive oil water in a small bowl. Microwave until sugar melts, 30 seconds. Brush apples and pecans with half of mixture. Reserve the rest.
Bake in centre of oven until a tester inserted into centre of cake comes out clean, about 45 minute Transfer to a rack. Brush top of warm cake with remaining sugar mixture. Run a knife between the pan and the outer edge of the cake, then remove ring. Gently remove cake from base. Let cool completely, about 1 hour. Serve with whipped cream.
Keeps well at room temperature for up to 3 days.