Here’s a handwritten recipe for extending butter found in an old box of recipes. The top of the sheet is torn a bit but doesn’t affect the recipe at all. The recipe is below, typed as-is.

Extended Butter (follow in order)

In blender:

1 cup veg. oil (safflower or corn)

Add:

1 teasp. liquid lecithin
1/4 cup + 1 tab water*

Blend together then add:

1 lb room temp butter

Blend again, scrape sides.

Refrig. Makes 1 3/4 lbs.

*RecipeCurio Note: This part is unclear on the recipe, I believe it reads as “1 tab water”, meaning 1 tablespoon of water. It’s not close to looking like the “1 teasp. liquid lecithin” in the line above, so I went with tab.