Preheat the oven to 200°C / 400°F and line a baking tray with parchment paper.
Slice the eggplants into 1–1.5 cm thick rounds.
Arrange the eggplant slices in a single layer on the tray.
In a small bowl, combine the olive oil, thinly sliced garlic, red chili flakes, salt, and pepper. Let it sit for a minute to infuse the oil with flavor before brushing.
Brush the mixture generously over both sides of the eggplant slices.
Sprinkle fresh thyme leaves on top.
Roast for 25–30 minutes, flipping halfway through, until the eggplant is golden, tender, and slightly crispy on the edges.