Spread the chickpeas out onto a few layers of paper towels, and pat dry. Spread them out onto two rimmed cookie sheets and drizzle with olive oil. Gently shake the pan to coat with oil, then sprinkle with salt. Roast for 30-40 minutes, until brown and crispy, shaking the pans every 10 minutes or so so they don't burn.
Transfer to a large mixing bowl and toss with garam masala.