Melt butter in a large skillet over medium heat, and cook and stir the garlic and bay leaf until the garlic is lightly browned, about 5 minutes. Stir in the chicken stock and white wine, and increase heat to a full boil. Cook the sauce, stirring often, until reduced to 1 cup, about 15 minutes. Remove bay leaf. Lay the bok choy halves, cut sides down, into the sauce, and reduce heat to a simmer. Cook until tender, about 10 minutes. Serve with sauce spooned over bok choy.