I got this recipe from Denise's Blog An English Girl Rambles. It is what she makes for her birds in the winter in her home in America, I do something similar and add Wild Bird Seed rather than the peanut butter. The birds love the home made food over the shop bought fatballs. I never have the chance to freeze any as my birds invite all their friends and fill up on my concoctions keeping us busy making more. The RSPB has recipes from various celebrities for winter food for our birds CLICK HERE to downlooad them
2 cups (1 block) lard
1 cup Crunchy Peanut Butter
1 cup Oatmeal
1 cup unbleached Wholemeal flour
1 cup of cornmeal or wheat germ
Melt the lard a little in a big glass bowl (30 seconds in the microwave) and mix all of the ingredients together. It gets a bit messy. Line a rectangular pan with a sheet of wax paper and press the mixture in. Pop it in the freezer for an hour or so, then cut into blocks. The smaller ones work best (4" x 2"), because the birds eat it quickly. It won't have a chance to collect mildew if you put this out in the summer when it is hot and humid. I normally use them in the wintertime when I feel the birds really need some extra sustenance. Store the blocks in a Ziploc bag in the freezer and refill your suet feeder as needed.