Heat 1/4 inch oil in a 10-inch heavy skillet over moderate heat until hot but not smoking, then cook bread, stirring frequently, until deep golden, about 1 minute. Transfer with a slotted spoon to paper towels to drain. Tie thyme, parsley, chives, and bay leaves together with kitchen string to make a bouquet garni. Bring lentils, chestnuts, water, bouquet garni, and 1 1/2 teaspoons salt to a boil in a 3-quart heavy saucepan. Simmer, partially covered, until lentils are tender, 20 to 25 minutes. Discard bouquet garni and reserve 2 cups cooking liquid. Puree remaining soup in 2 or 3 batches in a blender (use caution when blending hot liquids), then pour through a large sieve into a large bowl, discarding solids. Whisk in enough of reserved cooking liquid to reach a thin, creamy consistency, then season with salt and pepper. (Soup will continue to thicken as it stands; keep reserved cooking liquid on hand to thin as needed.) Preheat oven to 325°F. Puree foie gras, whole eggs, yolks, and remaining teaspoon salt in a food processor until very smooth. With motor running, add 1 cup cream in a stream and blend until just combined (do not overprocess, or cream will curdle). Put soup plates on 2 large baking sheets, then divide custard among them. Bake in upper and lower thirds of oven until just set, 15 to 20 minutes (some custards will cook quicker than others; check each one). Cool to warm. Reheat soup, stirring occasionally, until very hot. Beat remaining cup cream until it just holds stiff peaks, then vigorously whisk whipped cream into soup. Pour soup over custards and sprinkle with croutons and almonds.