Follow the focaccia dough recipe up until it's time to tip it into tray.

While the dough is proofing, peel and thinly slice the onions. Melt the butter in a large frying pan over medium‑high heat, then add onions, tossing to coat. Lower the heat to medium. After 10 minutes, sprinkle in sea salt and pepper. Cook slowly, stirring every 3–4 minutes, until the onions turn golden brown and soft. If stuck, deglaze with a few tablespoons of water or stock and scrape up the browned bits.

While the onions cool, grate the cheese.

Tip the focaccia dough into your oiled tray (as per your dough recipe). Scatter ⅓ (75 g) of the grated cheese and ½ of the caramelised onions over the dough. Fold and flip the dough as shown in video. Cover the tray and proof at room temperature for 1-1.5 hours, until the dough rises and fills the tray.

Set your oven to 220C/430F.

Drizzle olive oil over the dough and dimple. Sprinkle over flaky sea salt. Bake on the lowest rack for 12 minutes.

Remove focaccia from oven and sprinkle over half of the remaining cheese. Evenly distribute the remaining caramelised onions above that layer. Add the rest of the cheese on top of the onions. Add freshly cracked pepper if you wish to. Return to oven and bake for another 10–12 minutes, or until cheese is bubbling and golden.

Remove from oven, transfer to a cooling rack. Allow to cool for at least 15 minutes before slicing. Serve and enjoy!