Cognac Deep-Caramel Onion Soup Gratinée

Method

1. Halve the onions and slice them 5 mm thick along the grain; slice the shallots thinly. A slightly thicker cut stops them melting away during the long cooking and keeps a little bite.

   Add in this stepOnions 600 gSmall shallots 2

2. Melt the butter in a 24 cm cast-iron or stainless steel pot over medium heat, then add the onions, shallots and a pinch of salt. Cover and cook for 15 min, stirring now and then, until completely collapsed with liquid pooling at the bottom.

   Add in this stepButter 35 gCoarse sea salt to taste

   medium heat

3. Uncover and raise to medium-high heat to drive off the liquid. Now, for 40 min, repeat this cycle: leave the onions mostly unstirred until a deep brown film forms on the bottom of the pot (about 6 min per round), then add 2–3 tbsp water and scrape the bottom hard with a wooden spoon, working it into the onions. After 3–4 rounds the onions turn dark mahogany, sweet and savory. If the film heads toward black rather than brown, add water immediately.

   Add in this stepWater (for deglazing, used in several splashes) 90 ml

   medium-high heat

4. Take the pot off the heat and pour in the cognac (pouring over a flame can ignite it), then return to medium heat and scrape the bottom. Add the white wine and boil for 2 min until reduced by half.

   Add in this stepCognac (or brandy) 2 tbspDry white wine 100 ml

   medium heat

5. Add both stocks, the thyme and bay, bring to a boil over high heat for 4 min, then lower to low heat, set the lid ajar and simmer for 25 min. Remove the herbs, add the sherry vinegar to brighten the flavor, and season with salt and pepper.

   Add in this stepBeef stock 550 mlChicken stock 250 mlFresh thyme sprigs 3Bay leaves 1Sherry vinegar (or white wine vinegar) 1 tspCoarse sea salt to tasteBlack pepper to taste

   high heat→low heat

6. Butter the bread thinly on both sides, place on a baking tray and bake in the oven preheated to 180°C for 8 min. It should be dry and crisp right through, so it doesn't turn soggy in the soup. Rub with the cut side of a garlic clove.

   Add in this stepBaguette or country bread, 1.5 cm slices 4Soft butter (for the bread) 10 gGarlic cloves 1

   oven

7. Raise the oven to 250°C (grill setting). Fill ovenproof bowls 80% full with soup, scatter on a little grated Gruyère, add the croutons, drape the Gruyère slices over so they hang over the rims, and sprinkle with Parmesan. Bake on the top shelf of the oven for 4 min, until the cheese is crisp and charred where it touches the bowl.

   Add in this stepGruyère (half grated, half thinly sliced) 70 gParmigiano Reggiano, grated 20 g

   oven