Every writer has a writing nemesis. For some, it's weapons. For others, it's attire.
For me, it's food.
Not that I have anything against food, I love food! I just don't want to think about my hero or heroine chewing--ever.
Unfortunately, a hero can't go ten days without a bite to eat. It's just not realistic.
Food is essential for survival. So, when I'm in a bind to find what historical snack my heroine should be munching, I take a look at these sites.
The Food Timeline
This timeline, created by a reference librarian, is a great site for checking whether your heroine can eat funnel cake in 1860. (By the way, she can't. Funnel cakes didn't exist until 1879.) The site also includes a variety of books on cooking and household management, like Mrs. Beeton's Book of Household Management (1861).
The Food Museum Online
So, this site probably won't ever have exactly what you're looking for, but it's got some great temporary exhibits.
Check out these recipes! This site run by Ivan Day, one of the foremost authorities on food history, is a great place to learn what's in some select historic British foods. Plus, you can get great ideas on how historic tables were set in the galleries section.
The History of Food
This collection of links from the International Guild of Hospitality and Restaurant Managers covers almost everything imaginable from etiquette to recipes.
Michigan State University Libraries bring us this wonderful selection of cookbooks from 1798 to 1922. Cookbooks can be searched by date or interest.