Preheat oven to 225ºF (110ºC). Brush 4 parchment-lined baking sheets (15 x 11-in./38 x 28-cm) with olive oil.
Use mandoline slicer (with guard) to slice carrot, parsnip, sweet potato and beet into 1/16-in. (2-mm) thick slices. Arrange in single layer on baking sheets. Bake, rotating sheets occasionally, 60 to 75 min. or until chips are dried and slightly crisp. Transfer sheets to wire racks to cool completely.
Meanwhile, in bowl, mix ricotta, yogourt and garlic powder. Fold in feta. Serve with veggie chips.
Add 1 tsp (5 mL) finely grated lemon zest to dip.