Preheat oven to 400°F.
Toss zucchini coins with olive oil, salt, and black pepper.
Spread on a baking sheet in a single layer.
Roast for 15–20 minutes until edges are lightly browned.
Season cod with salt and black pepper.
Heat a pan over medium heat and cook cod for 3–4 minutes per side until lightly golden.
Melt butter in a small pan and add garlic and chili flakes.
Cook briefly, then remove from heat.
Spoon a thin layer over the cod.
Serve with roasted zucchini.