THE panade is the simplest of soups, nothing more than a 1 puree of bread which has been steeped in water, and to which one can add egg yolks and butter. This variation on the panade, a typically brilliant improvisation by Richard Olney, unifies the technique of French onion soup - the long, slow cooking and caramelisation of onions - and allies it with the panade. It is stupendous.
Onion Panade
4 very large onions, thinly sliced Salt. 60g (2oz) butter. 250g (8oz) dried bread, thinly sliced. 150g (5oz) freshly grated Parmesan and Gruyere. Lightly salted boiling water.
Cook the onions, lightly salted, in the butter over a very low heat, stirring occasionally, for about one hour, keeping them covered for the first 40 minutes. If the heat is low enough and the saucepan of a heavy material, there will be no problem of colouration - they should begin to caramelise lightly toward the end of an hour, at which point the flame may be turned up slightly and they should be stirred regularly until the entire mass is of a uniformly rich caramel colour. Should there be signs of colouration too soon, the flame should be lowered even more, or the heat may be dispersed by separating the pan from the flame with an asbestos pad.
Spread slices of bread thickly with the onions, arrange a layer in the bottom of the casserole, sprinkle over a thick layer of cheese, and repeat the process, packing each layer gently and arranging the bread slices as well as possible to avoid empty spaces.
The onions should be used up on the next to last layer of bread, the last layer being sprinkled only with cheese, and the casserole should not be more than two thirds full at this point.
Pour in the boiling, salted water, slowly and very carefully, at one single point against the side of the casserole, permitting the bread to swell and the mass to rise until obviously just floating, but no more (if you fear an unsteady hand, carefully ease the tip of a funnel down the side of the casserole to the bottom and pour the boiling water into the funnel).
Cook on top of the stove, uncovered, over a very low heat, the surface maintaining a light, slow bubble for half an hour. Add, as before, just enough boiling water to be certain that the body of the bread is submerged, sprinkle a bit more cheese over the surface (sprinkle over Cognac now, if you like), shave paper-thin sheets from a firm, cold block of butter, distributing them over the surface. and transfer the casserole to a medium oven (350'F, 180'C, gas 4) for one hour, raising or lowering the temperature, if necessary, after about 40 minutes. depending on how the gratin is developing.
The soup should he covered with a richly coloured crust of gratin and should he served out with a large spoon on to preheated plates.