Preheat the oven to 350 degrees F. Spray two 8-inch round cake pans with cooking spray, or butter and flour them.
Warm the oil in the microwave until it is softened or even melted but not hot to the touch, up to 30 seconds, then pour it into the bowl of a stand mixer fitted with the paddle attachment. Add the yogurt, brown sugar, applesauce and vanilla, and mix until combined.
Sift together the flour, cocoa powder, baking powder, baking soda and salt in a medium bowl.
With the mixer on low, slowly add 1/3 of the dry ingredients to the yogurt mixture, then 1/4 cup of the milk. Repeat with the rest of the dry ingredients and milk. Remove the bowl from the stand mixer, and fold in the chocolate chips. Divide the batter between the prepared cake pans.
Bake until a toothpick inserted in the center comes out clean, 22 to 26 minutes. (Cooking times vary depending on the quality of the ingredients and weather conditions.) Let the cakes cool in the pans for 5 minutes, then transfer them to a wire rack to cool completely.
To assemble: Rinse the grapes, raspberries, blackberries, blueberries and strawberries until they're shiny and clean.
Place 1 cake layer on a cake stand, and top with about 3/4 cup whipped cream. Place a strawberry that's 1 to 1 1/2 inches high upside-down in the center of the cake. (This will help keep the cream from smooshing out when you add the next cake layer.) Spread some of the fruit around the edges of the cake. Because this is a naked cake, you will want to pay attention to how you place the fruit on the edge.
Place the remaining cake layer on top. Starting with a bunch of grapes still attached to the vine, place the grapes on the cake, then start building up around them. Fill in with the raspberries, blackberries and blueberries, and place a few more grapes around to balance the color. Finally, place some strawberries around the edge and maybe even 1 on top.
Drizzle the chocolate syrup over the cake, and chill until ready to serve. If using confectioners' sugar, sprinkle it over the top immediately before serving.
Recipe courtesy of Amanda Rettke