Adillo is correct. Use the "advanced search" part of Google.
In the "exact phrase" box, type in things that are more than one word, like "chocolate chip cookies" (no quotes)
In the bottom most box where it asks for domain, type what Adillo said: www.discusscooking.com
And if you know anything else, like the poster's name, you can type that in the top-most box.
Click enter and your options are often narrowed down to the exact thread or even post.
Google is an amazing and wonderful thing!