There are several recipes for pumpkin syrup on the internet, and there's nothing wrong with them, except they are not the kind of syrup that I wanted.
I wanted a true flavoring syrup, like they have in coffee shops and bars. Many recipes that I found were made with pumpkin puree and ground spices. This made the syrups thick, pulpy, and full of gritty ground cinnamon, nutmeg, and cloves. I prefer drinking coffee to chewing it, and I also wanted to make a batch of pumpkin soda. I wanted the consistency of water and without any floating pulp or spice sediment.
Anyway, here it is. You'll need:
1. One whole sugar pumpkin, about the size of a human head.
2. A juicer.
3. Whole spices: cinnamon stick, allspice berries, whole cloves, dried chopped ginger, and whole nutmeg.
4. A strainer
5. A pot.
Step 1: Juice Your Pumpkin
Sugar pumpkins are the ones typically used for eating, so that's what I started with. I chopped one side of it off with a kitchen knife and scraped out the stringy insides. I chopped the flesh into slices and fed them into a juicer. Using pumpkin juice rather than puree I hoped to achieve the thin, pumpable, and completely soluble flavoring syrup that you see on the shelves in the gourmet foods aisle.
As long as you don't let it sit too long and get desiccated or decayed, you can use a not-too-old jack-o-lantern for the pumpkin juice. Jack-o-lanterns can be eaten too, but probably don't taste as good as fresh sugar pumpkins.
From a sugar pumpkin about the size of my head, I obtained about 1 L of bright yellow-orange pumpkin juice. Noticing a large amount of foam on the top and pulp on the bottom, I strained the juice into another container. This reduced the juice to about 700 mL and left about 3/4 cup of pumpkin pulp behind.
Step 2: Steep Whole Spices.
I knew that I would never be able to strain out ground cinnamon, cloves, nutmeg, allspice, and ginger, so I opted to use whole spices.
Translating the classic pumpkin spice mixture into an equivalent amount of whole spices was something I had to just guess at. I ended up using two long cinnamon sticks, about 20 whole cloves, about 1/5 of a whole nutmeg, coarsely chopped, about 12 whole allspice berries, and about one tablespoon of dried chopped ginger root pieces.
I covered the pot and let it simmer for about 30 minutes. My house quickly began to smell like heaven itself, or maybe a quaint colonial village, minus the dysentery. I stirred the mixture every few minutes to remove the foam that formed. After 30 minutes, I let the mixture sit for an hour or so while the spices continued to steep.
Step 3: Strain and Sweeten.
Next I removed the cinnamon sticks and poured the juice through a strainer again. My pumpkin juice had been further reduced to 600 mL, so I added 100 mL of water to bring it back up to its original concentration. Regrettably, the steeping process changed the brilliant yellow-orange color of the juice to an unfortunate puke color.
Simple syrup, as it's name implies, is a straightforward affair. One part sugar to one part water. Treating my seasoned pumpkin juice like water, and doing some sloppy calculations to account for the sugar content of the pumpkin juice, I rinsed out my pot, added two and half cups of sugar to it and poured in the 700 mL of seasoned pumpkin juice. I heated the mixture until there was no grittiness left from the sugar and it was all dissolved. This increased the amount of syrup to about 1.2 L.
Step 4: Enjoy!
And that's it. Pour it in your coffee, steamed milk, or hot cocoa, make a pumpkin soda or cocktail, add it to a milkshake, or put it in a fancy bottle for a gift.
You will notice that it is a bit thicker than most coffee flavoring syrups, but you will find no sediment, pulp, or grit when you get to the bottom of your cup.
Let me know how yours turns out!