is he fix ? if not then there might be a female in heat around your house out side

By “making muffins” I’m going to assume that you mean that kneading thing that cats do with their front paws.
I read from a book once — “Why do cats do that” or some-such title, it was — that the kneading action is a sign of contentment (dating back to their kitten days, when they kneaded their mother’s belly to stimulate her to release some of that milk for them). I’d imagine that your cat is just showing you that he is totally content in all ways… “letting it all hang out,” if you will.
I know my horses usually have their equipment out when they’re really content.

What is making “muffins”?
I’m not familiar with this expression.
I’ve only been a “kitty” mom since July.

Oh, I saw my kitty’s “wee wee” for the 1st time a few days ago. I feeling I felt about that was that my Baby was growing up.

You have more issues than sports illustrated…

The answer is obvious and perhaps did not need to be asked. He finds this activity stimulating.

good luck!