Buttermilk is a very pretty word. It seems like it should taste a bit better, given the name. Anyway, I feel like whenever I buy a litre of buttermilk I use half and don't finish before the expiration date. This is a list of recipes that, together, use one full litre. Of course, there are always pancakes (Snowy & Chinook ones), too...

Cocoa buttermilk cupcakes, un-iced. I tried some buttermilk icing, it was good, but these are best plain.

Chocolate cherry oatmeal cookies (add teaspoon or two of regular milk if the dough doesn't hold together).

I used the homemade cupcake liners (see below) for these cornbread muffins (via apples & butter) — however, to tell the truth I was multi-tasking and used twice the amount of baking soda on this batch by accident and they were slightly horrible. The recipe is good, though, I promise ^_^

You can make cupcake liners by smooshing a square of paper over a glass. About 6" is a good size of paper for a liner. You can use origami squares, for example. I would try to choose paper that is not too chemically treated and coated — this is parchment paper.