Preheat the oven to 375°F (190°C). Lightly grease a round baking dish with olive oil or cooking spray.
In a small bowl, whisk together the balsamic vinegar, olive oil, minced garlic, thyme, salt, and pepper to make the glaze.
Arrange half of the sliced potatoes in the baking dish, overlapping the slices slightly. Drizzle with half of the balsamic-thyme glaze.
Layer the remaining potatoes over the first layer. Pour the rest of the glaze on top and gently press the layers down to compact.
Cover the dish with foil and bake for 45 minutes, until the potatoes are tender.
Remove the foil. If using, sprinkle grated Parmesan over the top. Bake uncovered for another 15–20 minutes, until the edges are crispy and golden.
Let the torte rest for 5 minutes before slicing and serving.
Notes
For even slices and optimal crispiness, use a mandoline slicer.
Substitute thyme with rosemary, or add red pepper flakes for a spicy variation.
This dish can be assembled ahead and stored in the fridge until ready to bake.