For the Waffles:
* 1 small sugar pie pumpkin (2 to 3 pounds)
* 2 1/4 cups all-purpose flour
* 1 teaspoon baking powder
* 1/2 teaspoon baking soda
* 1 teaspoon salt
* 2 teaspoons pumpkin-pie spice
* 1/2 cup packed light brown sugar
* 2 large eggs, separated
* 1/4 cup plain Greek yogurt
* 1 cup whole milk
* 4 tablespoons unsalted butter, melted
For the Topping:
* 1/4 cup slivered almonds
* 1/4 cup raw sunflower seeds
* 1 1/2 tablespoons pure maple syrup
* Coarse salt
* 1/4 cup dried cherries or cranberries
* Whipped cream, for serving (optional)
Prep the pumpkin: Preheat the oven to 350 degrees F. Remove the stem and cut the pumpkin into quarters with a serrated knife. Scrape the seeds and pulp into a strainer; set aside.
Roast the pumpkin: Put the wedges on a baking sheet and cover tightly with foil; bake until the flesh is tender, about 1 hour, 30 minutes. Remove the foil and let cool.
Puree and strain: Scoop the pumpkin flesh into a food processor and puree until smooth. Transfer to a sieve set over a bowl to drain the excess liquid, about 1 hour.
Toast the seeds: Meanwhile, reduce the oven temperature to 300 degrees F. Rinse the seeds under cold water and discard the stringy pulp; blot dry. Spread the seeds in a single layer on a rimmed baking sheet and bake about 30 minutes, stirring occasionally (this helps dry them out).
Make the topping: Transfer 1/2 cup pumpkin seeds to a bowl and add the almonds, sunflower seeds and syrup. Spread on 2 baking sheets lined with silicone mats or parchment paper and season with salt; bake until just golden, stirring several times, about 20 minutes. Cool completely on the pan, then toss with the dried cherries.
Make the batter: Whisk the flour, baking powder, baking soda, salt and pumpkin-pie spice in a bowl. Whisk the sugar and egg yolks in a separate bowl, then whisk in 1 1/2 cups strained pumpkin puree, the yogurt and milk. Whisk in the melted butter. Pour the pumpkin mixture into the flour mixture and stir with a rubber spatula until just combined (it will be lumpy). Beat the egg whites with a mixer until stiff, then gently fold into the batter.
Cook the waffles: Preheat a waffle iron and grease it if it's not nonstick. Spoon in the batter and cook until golden brown. Keep warm in a 250 degree F oven (directly on the rack) until serving. Serve with whipped cream, if desired, and sprinkle with the topping.