Melt butter in heavy Dutch oven over low heat. Sir in milk and condensed milk. Add all chips, stirring constantly, until mixture is smooth. Remove from heat. Stir in marshmallow cream, and vanilla and almond extracts. Stir in walnuts. Spoon into buttered 15x10x1" jellyroll pan. Sread evenly. Chill and cut into squares. Store in refrigerator.