Cut the pumpkin into bite-sized pieces and remove the core. Toss with some honey and the cinnamon sugar, arrange on a baking sheet, and bake at 160 °C (320 °F) for 45 minutes.
While the pumpkin roasts, combine the crème fraîche and Greek yogurt in a bowl.
In a small pan over medium heat, toast the hazelnuts with the brown sugar, butter, and 3 tablespoons of honey for 5 to 7 minutes, stirring occasionally, until fragrant and lightly caramelized.
Remove the pumpkin from the oven and roughly puree it with a hand blender, leaving some small pieces intact. Cut the apple into small pieces and fold in.
Divide the crème fraîche mixture among 5 glasses, top with the pumpkin puree, then sprinkle the hazelnut topping over each.