For the crumble, combine all-purpose flour, brown and white sugars, and cinnamon in a medium bowl. Stir with a fork to combine. Slowly drizzle in butter, continuing to stir with fork until all flour is incorporated and large crumbles form. Add pecans and pepitas and stir gently. Set aside.

Preheat oven to 350˚F. Spray a 9-inch spring form pan with baking spray. Wrap the bottom and up the sides of pan with heavy duty (or 2 layers) of foil. (The cake bakes for at least an hour; the foil will keep the sides and bottom from browning too much during the long bake.)

In a medium-size bowl, combine flour, baking powder, baking soda, cinnamon, cloves, nutmeg, and salt. Stir to combine and set aside.

In the bowl of an electric mixer, beat softened butter at medium speed for 1 minute. Add both sugars and beat another minute, scraping sides of bowl once or twice with a rubber spatula. Add eggs and beat until well combined. Again scrape sides of bowl to incorporate all ingredients. Add Greek yogurt and pumpkin and mix until combined. Remove bowl from mixer. Add flour mixture and stir just until flour disappears. Don't over mix.

Transfer half of the batter to the prepared springform pan. Spread evenly. Scatter about ⅓ of the crumble across the batter. Top with remaining batter and spread as evenly as possible. Scatter the remaining crumble over the batter.

Place spring form pan on a baking sheet. Bake on center rack of oven for 30 minutes then open oven and cover loosely with foil, taking care not to jar pan. Return to oven and bake another 30 minutes or until a toothpick inserted into the center of the cake comes out clean. Transfer to a cooling rack and allow to cool for 20 minutes, then remove sides of spring form pan. Cool for another 30 minutes, then drizzle icing over the top allowing it to drip down the sides. Serve cake warm or at room temperature.

While coffee cake is cooling, prepare the icing. Combine melted butter, brown sugar, maple syrup, and milk in a medium microwave-safe bowl.

Stir with a whisk or fork to combine.

Microwave on high for 30 seconds, then remove and stir again. Repeat 30 seconds in microwave and stir until smooth. Add vanilla and powdered sugar, whisk until smooth. Icing should be thick but still drizzle-able.