1Set the Ninja Foodi to Sauté function. Add butter and cook onion, carrots, and celery for 3 minutes.
2Add potatoes and vegetable broth. Close the lid and pressure cook for 5 minutes, then quick release.
3Add frozen peas, frozen corn, and thyme. Switch back to Sauté, then add flour and plant-based milk. Stir until thickened, about 2-3 minutes.
4Transfer mixture to an oven-safe dish. Cover with puff pastry sheet, trimming if needed.
5Place dish in air fryer basket and cook on Broil function for 10 minutes, until crust is golden and puffed.
6Serve immediately, straight from the dish.