Nectarine Upside-Down Cake in a Skillet

This is a cake I don’t remember my grandmother making, but it sure seems like a Grandma cake. It’s best eaten the day it’s made, but that shouldn’t be a problem because it’s so good. Make sure your cast-iron skillet is well seasoned. If not, scrub it well with a non-metallic scrubber, dry it, and lightly coat the interior with vegetable oil. Put the skillet in a 350°F oven for 3 to 4 hours. Cool and wipe clean, and you should end up with a smooth, shiny surface that’s essentially nonstick.