Preheat the oven to 180°C. Place 2 cups mixed (unpitted) olives into a sieve, and rinse under cold running water; drain well. Combine with 11/2 tablespoons each extra-virgin olive oil and lemon juice, 1 bruised garlic clove, 1 tablespoon rosemary leaves and a pinch of dried chilli flakes in a shallow ovenproof dish. Roast for 20 minutes, or until soft and fragrant. Serve warm, with drinks (see our Simple sangria recipe).
note The olive mixture can be put together up to 1 day ahead. Keep covered in the fridge, but take out 30 minutes before heating, if possible.