A commenter on my post from a few weeks ago  asked for the recipe for the beet cake that actually worked, and I’m glad to provide it. For this one I used about half a cup of beet puree and half a cup of squash puree, more or less. I’m pretty sure any combination would work, but your mileage may vary. This is a relatively quick and easy cake, good for a crisp fall evening — make it now while the beets are plentiful!
--1 cup cooked pureed beets* and/or squash, cooled. (I imagine sweet potatoes would work, too; your puree can be quite a bit waterier than if you actually meant to eat it)
--1/4 cup plain yogurt, buttermilk, or sour cream (I had some Greek yogurt and used that)
--1 1/2 cups sugar
--1/2 cup oil
--1/2 tsp salt
--1 tsp vanilla
--1 1/2 cups all-purpose flour
--3/4 cup unsweetened cocoa
--1/2 tsp baking soda
--1/2 cup chocolate chips, optional
Preheat oven to 350F
Butter or spray a 9-inch square cake pan
Whisk together the first 7 ingredients (puree through vanilla). Sift the flour, cocoa powder, and baking soda into the liquid ingredients, then blend them in, stirring only until you can't see any more flour. (Don't overmix.) Fold in the chocolate chips, if using, and pour into the prepared cake pan.
Bake for 30-35 minutes, until the top springs back when pressed lightly. Serve warm with ice cream (or plain) and see if anyone guesses what's in it.
*I had shredded beets left over from the previous week's disaster, so I put those in a microwave-safe bowl with water and steamed them until they were soft, then dumped all into the blender to puree. The squash was cut in half and the seeds, etc., scraped out, then turned cut-side down into a baking pan and baked at 350 for about an hour, or until soft, then scraped out of the skin and pureed in the food processor.