Place all of the ingredients in a small saucepan and place over a medium heat. Bring to a gentle simmer, stirring gently to ensure the sugar dissolves and doesn't burn or stick to the bottom.
Once the mixture simmers, turn off the heat and leave to cool gradually - let it sit for at least 10 minutes so that the flavors infuse the liquid better.
Once cool, strain through a fine mesh strainer to remove any coarser solids. Store in a bottle or jar in the fridge until needed.
Notes
To make a pumpkin spice latte or spiced coffee, you'll need around 1 tablespoon of the syrup per drink. For a latte, mix the syrup in with the shot of coffee and a little milk before adding the rest of the milk. If you like a sweeter drink, you may want a little more syrup. Note any finer spice solids may settle as the syrup sits. While you can mix them in, I find it generally better to just leave them to settle as they can be a little grainy to taste.