How do I ask businesses if they would like to buy my bread recipe?

It sounds like you started negotiations with this large business.  Before you go any further, you and this large business should sign a non-disclosure document, where both of you agree to keep all information confidential.  You don't want them to steal your receipe.  You really should find a Business Attorney, who handles mergers and acquisitions to help you.  The sale can be structured based on the negotiations between the large business and yourself.  It is not uncommon to ask for an upfront payment followed by royalities.  However, I would think that larger business would prefer a single payment as to avoid the paperwork and time in issuing periodic royality payments.  Again, this needs to be negotiated.