Preheat the oven to 350F and line the bottom of a 9-inch spring form pan with parchment paper. Spray the sides with a baking spray.
In a large mixing bowl, whisk together the yogurt, sugar, vanilla and eggs for a few minutes until creamy and smooth. Whisk in the oil, then set aside the wet batter. In a separate bowl, combine the dry ingredients: flour, baking powder, salt, cinnamon and nutmeg. Sift the dry ingredients in the wet ingredients, then mix together just until the flour is incorporated; do not overmix.
In a separate bowl, toss together the blueberries and cornstarch, coating the berries well; this will help keep the blueberry juices thickened as the berries cook in the cake batter. Reserve 1/2 cup of the blueberries for the topping. Add the remaining berries to the batter and fold in. Pour the prepared batter into the pan, spread evenly to the edges and level the top.
In a small bowl, prepare the crumble topping. Combine the oats, melted butter, brown sugar, pecans and a sprinkle of cinnamon. Toss the ingredients together until they are well coated in the butter. Sprinkle the mixture in an even layer over the cake batter. and sprinkle with the remaining berries.
Bake the cake in the preheated oven for 60 to 70 minutes, until a toothpick inserted into the center comes out clean. Once the cake is baked, remove it from the oven and cool in the pan for 30 minutes, then on a wire rack.
Prepare the whipped cream when ready to serve; I like to enjoy this cake warm. In a large mixing bowl, whisk together the chilled cream, vanilla and sugar for 3 to 4 minutes on high speed until stiff peaks form. Add the blueberry preserves and whisk again for about 30 seconds, just until combined. If desired, transfer the whipped cream into a pastry bag tipped with a star tip; I used Ateco tip #847.
Serve a generous amount of whipped cream on the side with each slice of this blueberry pie cake! Keep the leftovers well wrapped in plastic. This cake can stand at room temperature for 1 day and up to 1 week in the refrigerator. Keep the cream refrigerated.