Preheat oven to 425F.

Peel parsnips, then cut into ¼-inch thick matchstick fries. The skinnier they are the crispier the result. Try to cut them as close to the same size you can for even baking. Depending on how old the parsnips are or if they're very large, sometimes the centre core of the parsnip will be stringy, woody and tough, so it’s best to trim that out.

Transfer the parsnip to a large mixing bowl. Drizzle with oil, then sprinkle garlic powder and rosemary over top. Season with salt and pepper, then toss to coat.

Divide parsnip between two parchment-lined baking sheets. Spread out in a single, even layer. You don’t want to overcrowd the trays. Leaving enough space ensures browning, not steaming, so make sure each fry has some space.

Roast on the middle rack of the oven for 22-26 min, tossing halfway through, until golden and tender. 

While the parsnip fries roast, make aioli. In a small bowl, add mayo, mustard, maple syrup, vinegar, garlic powder and smoked paprika.  Stir to combine.  Season with salt, to taste. 

Transfer parsnip fries to a serving platter. Sprinkle with salt and pepper. Serve Dijon aioli alongside for dipping. Serve immediately.