Heat olive oil and pepper flakes in a small saucepan over medium heat for about 3 minutes to infuse the flavor of the pepper into the oil. Set aside.
Line a rimmed baking sheet with foil. Transfer cauliflower to the baking sheet and drizzle with infused olive oil. Toss with tongs to coat. Sprinkle chia seeds over the cauliflower and add salt and pepper to taste.
Bake cauliflower for 20–30 minutes, or until softened and just beginning to brown.