How to Butternut squash noodles into puree

I would steam and then mash with a potato masher.

Are you trying to puree cooked butternut squash? . If you purchased butternut squash, then I'd cook it first (roast it whole but pierce the skin several times with a knife; or, halve it with a good-sized chef's knife, remove seeds and pith, then bake or steam, then scrape the flesh from the tough skin, and purée it. I hope you'll provide more info so we can be of more help. Boil plain lasagne noodles (or use no-boil noodles), layer the (whole) noodles in a baking dish, alternating with the butternut squash purée and the other ingredients called for, then bake according to directions.

I'd steam them but in the microwave so the nutrients don't leach out. Sometimes I buy frozen cubes & they are already steamed.