In a medium bowl, combine the melted salted butter, granulated sugar, brown sugar, flour, and cinnamon. Mix with a fork until the mixture forms moist, pea-sized crumbs.

Place the bowl of streusel in the fridge to firm up while you prepare the batter.

Preheat your oven to 350°F (180°C). Line the bottom of a 9-inch springform pan with parchment paper and lightly grease the sides.

In a large bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, baking soda, salt, and pumpkin pie spice.

Create a well in the center of the dry ingredients. Add the oil, eggs, pumpkin purée, yogurt, and vanilla extract to the well. Whisk just the wet ingredients together first, then gradually pull in the dry ingredients around the edges.

Switch to a rubber spatula and gently fold the batter until everything is combined. The batter will be thick. Stop mixing as soon as the dry streaks disappear to keep the cake soft and tender.

Pour the batter into the prepared pan and spread it into an even layer. Sprinkle the chilled streusel evenly over the top.

Bake for 30-45 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean with a few moist crumbs attached.

Let the cake cool in the pan for about 10 minutes, then release the springform ring and transfer the cake to a wire rack to cool completely.

Whisk the powdered sugar, maple syrup, and heavy cream together in a small bowl until smooth.

Drizzle the icing over the cooled cake, slice, and serve.