Preheat the oven to 425°F (220°C).
Add butter to an 11-inch cast-iron skillet and place it in the oven while you mix the batter.
In a large mixing bowl, whisk the eggs until light.
Add in the remaining ingredients (almond milk, pumpkin purée, granulated sugar, vanilla extract, pumpkin spice extract, ground cinnamon, salt, and gluten-free flour blend) and whisk until well combined and no lumps remain. Ensure the batter is smooth.
With a hot pad, carefully pull the hot skillet out of the oven and pour the batter in immediately. The butter should be sizzling.
Return the skillet to the oven and bake until the pumpkin dutch baby is dramatically puffed and golden brown, about 25 to 28 minutes. Watch for the edges to climb high.
Cut the dutch baby into slices (similar to pie slices) and serve warm.