Measure the dry ingredients (flour, salt, sugar, yeast, and baking powder) together in a large mixing bowl or plastic container with a lid (if you are doing the overnight rise).

Sift the baking powder to remove any clumps, and whisk or sift everything together well.

In a smaller bowl or large liquid measuring cup, mix the milk and/or water and the pumpkin puree.

Whisk or stir the liquid ingredients until there are no lumps and the pumpkin puree is dissolved.

Stir the liquid mixture into the dry ingredients.

Mix the batter gently, stirring just until it is well mixed and uniform with no clumps of dry ingredients.

Cover the batter bowl with an airtight lid or wrap.

Let rest in a warm place for at least an hour, or until the surface of the batter is covered in bubbles.

To make ahead, mix the batter and let rest in the refrigerator overnight.

If you do the overnight rise, it's best to remove the batter from the fridge at least 30 minutes before making the crumpets to let it warm to room temperature and wake up the yeast.

The batter should be light and bubbly, and smell yeasty and fresh.

Heat a large griddle or heavy non-stick/cast iron pans over medium-high heat.

Test the griddle surface with a drop of water. When it dances and sizzles on the surface, it is ready. Reduce the heat slightly after the griddle is pre-heated.

If your crumpet rings are not non-stick, butter them for the first batch of crumpets (or if they begin to stick later).

Place the crumpet rings or metal cookie cutters on the griddle, butter the griddle (I use a stick of butter and lightly touch it to the surface inside each ring.

Immediately ladle about 1/4 - 1/3 cup of batter into each ring (use more for larger molds, less for smaller ones).

Let the crumpets cook for a few minutes.

Spin the rings slightly, and when the batter is mostly set and you can slide the crumpet slightly in the pan, carefully remove the ring. They will be hot! I use my fingers but you probably want to use tongs or a hot pad.

Remove the rings and carefully flip the crumpets when they are cooked at least halfway through. This is about 3-6 minutes on the first side, and 2-4 on the second for me, usually, though it varies with how large and thick you pour, how hot your burners are, and the thickness of your griddle (cast iron will retain heat better than a thinner griddle when the cold batter hits it).

You may have to adjust the heat to find the "sweet spot" for your particular griddle and stove, where the crumpets cook through without burning. This might take a bit of trial and error since every stove is different.

If the crumpets are not done all the way through, you can keep them on the edges of the pan to stay hot and keep cooking while you do fresh batches on the center of the griddle.

Refrigerate for longer storage (up to 3-4 days) or freeze leftovers.