For the creme fraiche topping: Whisk together the creme fraiche, vanilla extract, orange zest and vanilla bean seeds in a small bowl until combined. Cover and refrigerate for at least 30 minutes or overnight to allow flavors to meld.
For the poached maple pears: Meanwhile, combine 4 cups water, the sugar, cinnamon sticks, orange peel and vanilla bean in a high-sided medium skillet over high heat. Bring to a boil and cook until sugar has dissolved. Reduce the heat to a simmer, add the pears and cook, turning a few times, until a thin-bladed knife meets no resistance, about 20 minutes. Remove the pears to a plate and let cool, then then slice each half in half again.
Bring the poaching liquid back to a boil and cook until reduced to about 1 1/2 cups. Remove the cinnamon sticks, orange peel and vanilla bean. Add the maple syrup and the poached pears and cook 1 minute longer. Keep warm.
For the Dutch baby: Preheat the oven to 400 degrees F. Place the eggs in a blender and blend for 1 to 2 minutes, until smooth and pale in color. Add the flour, milk, brown sugar, pumpkin pie spice, molasses and salt, and blend until smooth.
Melt the butter in a 9-inch cast-iron skillet over high heat, swirling it up the sides to evenly coat the pan. Pour the batter into the skillet and immediately transfer to the oven. Bake until the pancake is puffed and browned, and crisp at the edges, 15 to 20 minutes.
Dust the Dutch baby with powdered sugar and cut into wedges. Top each wedge with creme fraiche topping, some poached pears and a drizzle of the pear syrup.