Preheat the oven to 200°C (400°F). Grease the loaf pan and line with a parchment sling, leaving overhang on the long sides. This batter has enough sticky bits (olives, cheese, tomato) that lifting a bare tin risks tearing the crust.

Whisk the flour, baking powder, bicarbonate of soda, salt, pepper, oregano and garlic together in a large bowl.

In a jug, whisk the sourdough discard, eggs, milk, olive oil and the reserved tablespoon of sun-dried tomato oil until smooth.

Pour the wet mixture into the dry and fold with a spatula until just combined. A few flour streaks are fine. Don't overmix, or the loaf turns tough rather than tender.

Spread the grated courgette over a few sheets of kitchen paper and press firmly to remove the surface water, without wringing it bone dry. Fold the courgette, 80g of the parmesan, the olives, sun-dried tomatoes and basil through the batter, keeping 20g parmesan back for the top.

Scrape the batter into the prepared tin and level the top. Scatter the reserved parmesan over the surface, plus a few extra olive halves if you like the look.

Bake for 15 minutes at 200°C (400°F), then lower the oven to 175°C (350°F) and bake for a further 45–50 minutes. Tent loosely with foil once the top is deep golden, usually around the 30–35 minute mark, so the crust doesn't overcook before the dense centre is done.

Check doneness with a skewer in the centre of the loaf, not just near the edges. A clean skewer from the middle is the only signal worth trusting on a batter this dense.

Cool in the tin for 15 minutes, then lift out using the parchment sling onto a wire rack. Let it cool at least 30–40 minutes before slicing for the cleanest cut, though it's fine to serve slightly warm if you can't wait that long.