Preheat your oven to 325 degrees F and spray a 9-inch springform pan with a nonstick spray. Wrap the bottom in foil and place it on a baking sheet. Set aside.
Begin with the crumbled topping. In a large bowl, stir together the flour, oats, sugars, cinnamon, ginger, cloves, cardamom, nutmeg and salt until fully combined. Gently stir in the melted butter and crumble the ingredients together. Set aside.
Next, prepare your pear coffee cake. In the bowl of your stand mixer, with paddle attachment fixed, cream together the butter and sugar for a about 1 minute or until light and fluffy. Add each egg, one at a time, and mix until incorporated. In a large bowl, whisk together the cake flour, baking soda, salt, cinnamon, ginger, cloves, cardamom, and nutmeg. With the mixer running on low, take turns adding the dry ingredient mixture and buttermilk to the creamed butter and sugar. Start with the dry ingredients and end with the dry ingredients until all has been added. Mix for about 1 minute or until light and airy. Mix in the vanilla extract. Pour the cake batter into the prepared pan and set aside.
In a medium bowl, toss together the pears, cornstarch and cinnamon. Layer the sliced pears evenly onto the cake batter. Top the pears with the crumbled mixture, making sure to evenly coat the entire top.
Place the cake in the oven and bake for 45 minutes to an hour or until a toothpick comes out clean. Remove from heat and allow the cake to cool in the pan for at least an hour before slicing and serving. Sprinkle the cake with sliced almonds and a dusting of powdered sugar before serving. Enjoy!