Preheat the oven to 428ºF/220ºC (regular setting, if using a convection/fan setting, set the temperature to 200ºC/400ºF instead) and line a baking sheet with parchment paper.
Peel the sweet potatoes, wash and remove the ends of the zucchini, press the garlic, and remove the stems from the thyme sprigs.
Slice the zucchini and sweet potatoes into thin discs, then transfer them to a mixing bowl and mix them with the olive oil, thyme, garlic, salt, and pepper, making sure all vegetables are coated.
Spread the vegetables out on the lined baking sheet, then roast for 35 minutes, until they're tender and beginning to crisp.
Serve right away or let cool, then store in an airtight container in the fridge for up to 3-4 days.