Trim the dark green tops from one spring onion and reserve them for garnish. Roughly chop the remaining spring onions, including the bulb and light green stalks.

Add the spring onions, garlic, pepper, and optional herbs to a food processor and pulse until finely chopped. Add the softened butter and blend until smooth and bright green, scraping down the sides as needed. Taste and add extra salt if needed.

Preheat the oven to 400°F. Slice the ciabatta in half horizontally. Using a knife, cut shallow crosshatch squares into the crumb of each half without cutting through the crust. This helps the butter melt and absorb into the bread.

Spread the spring onion butter generously over both halves of the bread, pressing some of the butter down into the cuts. Sprinkle ½ cup of the Parmesan evenly over the top.

Place the bread on a sheet pan and bake for 8–10 minutes until the butter is melted and bubbling and the bread is lightly crisp.

Turn the oven to broil and broil for about 1 minute until the Parmesan becomes lightly golden.

Remove the bread from the oven and sprinkle with the reserved sliced spring onion greens, the remaining ¼ cup Parmesan, and a pinch of red chili flakes.

If desired, pour or brush melted butter over the bread, allowing it to melt into the cuts and the crumb. This step is optional, but especially delicious with ciabatta because the bread stays crisp while becoming extra buttery.

Cut into squares and serve warm.