Big
at all the enablers on this thread. Cooking for your family is domestic labour, it can also be an act of love or at least consideration. A roast meal can take a good hour and a half to get together. You obviously want the fruits of your labours to be nicely presented and appreciated. Yes, it would also make my heart hurt if the man I'd decided to spend my life with thought so little of my work that he mushed it up, and particularly if he only does this with my cooking.
OP, this is just odd behaviour, don't listen to anyone normalising it. It's one thing to relax and be yourself at home, but we don't all live in a vacuum, we live with one another and once you start breaking down the basic social niceties of living with one another, you have to ask yourself - what's the point in cohabiting? We've probably all got the odd unpleasant habit - spot squeezing, nose picking, hair chewing - but most of us don't indulge in front of others. It's gross, and rude. OP's husband is being gross, and rude, and teaching his baby how to behave too. And as several people have pointed out here, it's a real turn-off sexually too.
I don't think the silly suggestions of pureeing the food are going to help - why descend to his level? - nor that you make him toddler food while you make your own meal - why should you cook two meals? You need to sit down with him and explain clearly, as if to the hard-of-thinking, that his adult behaviour is like that of a child, that it's disgusting to watch, it turns you off him, and he needs to exercise the same self-control that he evidently does when eating out. And if he digs his heels in - well, I'd be wondering what other antisocial or disgusting habits might rear their heads in the future, and whether I wanted to stick around.
It's very interesting that he's only started this nonsense two years ago (so, not autistic behaviour, not a food sensitivity issue!) and presumably when you were pregnant with your now one-yr old. Hmmmm. Does he show his disquiet at not being the only other person in the house, or that a baby is competing for his attention, in any other ways?