Preheat the oven to 450 degrees F. Add a teaspoon of butter into the cups of popover pan and place it into the oven.
Combine flour, chopped rosemary, sage, grated parmesan, and salt in a medium bowl. Whisk together until combined.Combine eggs, pumpkin puree, and whole milk to a large mixing bowl. Use an electric hand mixer to mix together for 3 minutes, until frothy.
Add melted butter and continue to blend for another 15 seconds.Fold dry ingredients into the pumpkin mixture.
Carefully remove the popover pan from the oven. Pour batter into the popover pan cups until 3/4 the way full.
Place bake into the oven and bake for 20 minutes at 450 degrees F. Then reduce the temperature to 350 degrees F and continue to bake for 18-20 minutes, until tall and golden brown.Let the popovers cool on a wire rack.
Notes
Do not open the oven door during the cooking process! The popovers will either rise and collapse or not rise at all.
Be sure to whip your ingredients for at least 3 minutes. Beating air into the pumpkin mixture will allow it to rise in the oven!
Bake the popovers on the lower rack in the oven. This will allow the popovers to rise without hitting the top of the oven rack. If you need to remove an oven grate, I highly suggest it!
Use room temperature eggs and milk to prevent having to overmix your batter.