Cookies are tricky things to call single serve, since no one ever makes a batch of those expecting to eat them in one sitting. This is a recipe for biscotti I got off some guy's website years ago, it was apparently his straight-from-Italy-to-New Jersey grandmother's recipe. I'm usually the only one in the house who eats these things and I don't have a hard time consuming a full recipe of these within a few days:
1 1/2 c flour (approximate)
3/4 tsp baking powder
2 tbs shortening (use butter flavored Crisco if you have it, really good in this recipe)
1/2 c sugar
flavoring (any liqueur or flavor extract -- I've used a dash of Frangelico to excellent effect, Limoncello also works well)
Preheat oven to 375 degrees Fahrenheit (about 200 C). Combine ingredients and knead the dough together. Add more flour to the dough if needed (depending on how much of your flavoring you used.) Form the dough into a long rectangular loaf, shaped something like a ciabatta. Bake on a greased cookie tray for 20-25 mins, then slice it up into biscotti pieces, and bake them on the same tray for another 5-8 mins. Yields about 18 cookies.
Check out the source page for some fun historical material. "Some of Nunziata's children used to eat these biscotti for breakfast, spread with butter and then dipped into American coffee (This was when children used to drink coffee for breakfast)."