Prepare a mold for your seed cake. A springform pan is the easiest to use, but you can use a silicone mold, or a plastic deli tub. or even form a mold out of heavy tinfoil. If the mold doesn't come apart or turn inside out, line it with tinfoil, parchment paper, or a coffee liner so you can remove in one piece.

If you are planning to make a solid cake that sits on a platform or is inserted into a suet feeder, go to the next step.

If you are planning to hang your birdseed cake by string without a feeder, or to insert it onto a feeder platform with a central prong, roll up some tinfoil or heavy paper into a rod shape and set it up in the middle, to keep a space open.

In a pot, warm the shortening and peanut butter over medium-low heat, stirring until it is combined.

Stir in the rest of the ingredients until they are combined, and pour the mixture into the mold. Press it into place as compactly as you can, so it will hold together.

Freeze for several hours until the cake is solid. Remove from the mold and peel off any liners and center bits. Add a loop of string to use on its own, or insert the cake into a bird feeder.