Not sure you need to make such, to provide the extra calories during cold weather. MOST chicken owners simply add some cracked corn to the chickens diets. Corn does generate calories that increase body heat production.
But there is no reason not to experiment. Take a stick of butter and melt it. Into it, add wild bird seeds until all butter is absorbed and you have a paste like mixture. Place into a container, that will be easily removed, and set into freezer to congeal mixture. Not long, and you will have a semi solid brick. Give to your hens to taste/ try/ sample. If they don't like it, then set outside for songbirds. I suggest butter because margarine is hydrogenated oil , that molecule is only one atom different than vinyl siding. I believe butterfat is healthier. JMO.
WISHING YOU BEST
