- 60 gm butter, coarsely chopped
- 2 tbsp olive oil
- 4 onions, thinly sliced
- 2 tbsp thyme leaves
- 2 garlic cloves, finely chopped
- 1.5 litres (6 cups) vegetable stock
- 6 slices day-old rye bread
- 200 gm Cantal (see note), coarsely grated, plus extra to serve
- 1Preheat oven to 180C. Heat butter and oil in a casserole over low heat until melted, add onion, cover, stir occasionally until tender (35-40 minutes), uncover, increase heat to medium and stir occasionally until caramelised (10-12 minutes). Add thyme and garlic, stir occasionally until tender (2-3 minutes). Add stock, bring to the simmer and set aside.
- 2Layer bread and two-thirds of the cheese in a 6-litre ovenproof casserole, pour hot soup over, season to taste, cover and bake until golden and bubbling (20-25 minutes).
- 3Preheat grill to high heat (see note). Scatter soup with remaining cheese and grill until cheese is bubbling and golden (4-5 minutes). Serve hot.
Note Cantal, a semi-hard cow's milk cheese from France's Auvergne region, is available from select delicatessens. If it's unavailable, substitute 100gm raclette and 100gm Gruyère. If you can't fit a casserole under your grill, preheat oven to 220C and bake soup uncovered until cheese is golden and bubbling. Drink suggestion by Max Allen