Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
Peel and dice the gold potato into small chunks, then boil in a pot of salted water for 12-15 minutes until tender.
While potatoes boil, prepare three small bowls for dredging: one with flour, one with the beaten egg, and one with panko breadcrumbs seasoned with a pinch of salt and pepper.
Pat the cod fillet dry with a paper towel, then dredge it lightly in flour, dip into the egg, and press firmly into the panko until evenly coated.
Place the coated fish on the baking sheet, mist the top with olive oil spray, and bake for 12-15 minutes until the crust is golden and the fish is opaque.
Steam the broccoli florets over boiling water for 5 minutes until they are bright green and tender-crisp.
Drain the potatoes and mash them thoroughly with the Greek yogurt and your choice of fresh herbs like chives or parsley until smooth and creamy.
Serve the crispy baked fish alongside the herbed mash and steamed broccoli.