Preheat oven to 400F.
In a large skillet, melt butter over medium heat. Add onions and sweat them for 15 minutes or until golden brown. Once the onions are sweet and tender, add the livers and raise the heat just a bit. Cook until the livers are firm and cooked through, another 5-6 minutes. Add salt, pepper and thyme to the livers and onions. Place the mixture in a food processor and grind into a smooth spread. Transfer to a serving bowl.
While the livers cook, place bread on a cookie sheet and bake in the oven to dry out and toast, 5-6 minutes. Cut toasted bread slices corner to corner. Pile toast triangles onto a serving platter. Arrange ramekins or other small dishes with cornichons, shallots, Dijon, capers, honey mustard and lettuce leaves around the warm spread and toast points.
"I build my toast like this: mustard, liver spread, shallots, capers and a pickle on top," says Rachael. "Yum-O!"
Leftover spread can be chilled for several days.