When the meal was over and I took out my jar, shaking it to produce fresh whipped cream for spooning on top of slices of pie or cake, I didn’t think much of it — but everyone else did.
Full instructions are below, but here's a brief recap before you get started: Make the Cake: Combine oatmeal, baking soda, and water; let stand 20 minutes. Cream butter and sugars in another bowl.