Preheat oven to 375F and line a baking sheet with parchment paper.
In a small mixing bowl, combine olive oil, maple syrup, bourbon, salt, and cinnamon. Stir to combine.
Add pumpkin seeds to the bowl, stirring to coat well.
Transfer the pumpkin seeds to the prepared baking sheet, spreading them out evenly. If desired, give the seeds another sprinkling of salt.
Roast in preheated oven for 10-15 minutes, stirring after each 5-minute increment. Watch the seeds closely between 10 minutes and 15 minutes, as this is when they are most likely to burn. Roast them until they're light golden brown (mine generally take 12-14 minutes), which bakes the maple syrup enough so it will be crackly instead of wet/sticky when cooled.
Remove from oven and let cool completely on the baking sheet before serving.
Notes
It's important to make sure your pumpkin seeds are dry. If you've rinsed them after scooping them out of a pumpkin, be sure to towel dry them or air dry them, or even pop them in the oven at a low temperature for a few minutes. You can also buy raw pumpkin seeds online.
Make sure you're using real maple syrup, not pancake syrup.
Watch the pumpkin seeds very closely to ensure they don't burn.
Pumpkin seeds can be stored in an airtight container at room temperature.