Lay the chicken flat on a work surface. With a sharp fillet knife, remove the breasts and meaty parts of the thighs, leaving a thin layer of meat, about 1/8 to 1/4-inch thick, on the skin. Cut away and discard any tendons. Cut the removed meat into 1/2-inch cubes.

In a small skillet, melt the butter over medium-high heat. Add the onions and cook until soft, about 4 minutes. Add the garlic and cook for 30 seconds. Remove from the heat.

In a large bowl, combine all the ingredients except the poaching liquid, and mix well with your hands or a large wooden spoon. Shape the mixture into a block to fit inside the chicken.

Place the stuffing block in the center of the chicken, and cover with the left, then the right piece of chicken skin, stretching the skin to completely enclose the package. With twine and a long trussing needle, sew the chicken closed. Wrap the chicken in a piece of cheesecloth and tie around the ends and in several places in the center.

Bring the poaching liquid to a boil in a large pot. Add the wrapped, stuffed chicken and reduce the heat to medium-low. Simmer until cooked through, about 2 hours, turning and ladling the broth over the chicken as needed to keep moist during the cooking time. Remove from the heat and let cool partially in the broth. Place in a roasting pan and remove the cheesecloth. Wrap in plastic wrap. Place a large baking dish on top and weight to press the galantine into shape. Refrigerate at least 12 hours or up to 24 hours. Serve with tomato aspic and Creamy horseradish dressing.

Lightly grease a 9-inch baking dish with the oil and set aside.

Quarter the tomatoes over a sieve set over a bowl, saving the juices and discarding the seeds. Puree the tomato quarters in a food processor until smooth. Force the tomato puree through the fine mesh sieve, pressing hard to extract as much juice as possible. Discard the solids and measure the juice (you should have about 5 cups).

In a small bowl, combine 1/2 cup of the tomato liquid with the gelatin. Let sit 1 minute. In a small saucepan, heat 1 cup of the remaining tomato liquid to a simmer. Add the gelatin, stirring to dissolve. Remove from the heat and add to the remaining tomato liquid. Add the remaining ingredients, stirring well.

Transfer to the greased dish. Cover tightly with plastic wrap and refrigerate until firm, at least 4 hours and up to 24 hours. To serve, cut into 1-inch cubes with a knife and transfer to a serving platter.

Yield: 8 servings

In a small, non-reactive bowl, combine the shallots and vinegar, and let soak for 5 minutes. In a large, non-reactive bowl, place the shallots and vinegar, mustard, horseradish and garlic and whisk to combine. Slowly add the oil in a steady stream, whisking constantly until thick and all of the oil has been added. Add the salt and pepper and mix well. Slowly add the cream in a steady stream, whisking constantly.