When something like that happens to me, I find I have good luck when I fill the pan with water, add baking soda and salt and boil for a while. Hope you find a solution.

which type of calphalon is it?

My husband did that just after we bought the Calphalon. You don't want to use anything really abrasive because it will scratch it. I just poured boiling water in the pan and let it sit. It took a few times but it came clean.

It is just the solid silver kind - I think it may be aluminum.

stainless steel is what they are. I just bought some because i got a glass stove top.

try hot water & place a softner sheet in it, let it soak overnight.....Worked for me.....Michele

I use my spray oven cleaner on my stainless steel things- sink, teapot, pans, etc. Even the glass pans.

Try oven cleaner on it and let it set then see if will come off.

Coat the pan with Dawn dishwashing liquid, let set several hours or over night.
Girl Scout tip--before using a pan or pot over open campfire coat the pan/pot with a layer of liquid dish washing liquid.
Makes easy cleanup.

That is just what I was going to suggest.... My DH would do that to the pans when they cooked over an open fire on Canadian fishing trips. The clean up great!