From Pattern Union:
Phoebe Flares are an Add-on to the Phoebe Collection. They can be made as flared pants on their own, or added on to any of the Phoebe Tops. The pants feature gathered side inserts placed flatteringly just below the wide point of the hips and include front pockets. The waistband can be applied to the Phoebe Flares or use the waistband from the Phoebe Freebie.
Instructions include a video link for a sew-along.