If you opt to buy the pumpkin purée, that's totally fine. If you are a big fan of baking with pumpkin, check out my new e-book All About Pumpkin full of tips and tricks for getting the most out of fall's most beloved ingredient! Pumpkin purée versus pumpkin pie filling If you find that your baked goods made with pumpkin come out with a gummy layer on the bottom, consider straining the purée next time before baking with it. Some commercial brands can also be a little loose or watery and may benefit from straining.
And as for the leftover pumpkin purée, I froze it in ice cube trays, and I found that 10 iced cubes is equivalent to 1 cup of purée. You can save that pumpkin water and make bread with it or freeze it to throw into smoothies and pumpkin pie shakes. If you use homemade pumpkin purée for this recipe (or most any), it's very important to strain it through a cheesecloth to remove excess water, otherwise your pie filling (and other pumpkin baked goods) might end up soggy and wet.
