Mix together the chicken stock, vinegar, lemon juice, thyme, tarragon, and pepper in a bowl. Add the thawed artichoke hearts and toss to combine. Marinate in the refrigerator for at least 4 hours, or overnight. Drain the hearts and discard the marinade. Mix the goat cheese with the milk until smooth and creamy. Pipe the mixture onto the artichoke hearts with a pastry bag, or spoon it on using a small spoon. Melt the butter or margarine in a small skillet and sauté the garlic over low heat for 1 or 2 minutes. Add the bread crumbs and stir until lightly browned. Place the artichokes on a lightly greased baking sheet and sprinkle the bread crumb mixture over the tops. Bake in a 350F (180C) oven for 10 minutes, until heated through.
Serves 4 to 6.