I believe this recipe originated from the Baking with Julia cookbook and television series on PBS.
1 cup flour
1 cup cornmeal
1/2 tsp baking powder
1/4 tsp salt
4 Tbs unsalted butter, softened
1 cup sugar
2 large eggs
1 tsp vanilla
1 tsp finely grated lemon peel
1 cup raisins OR dried cherries, cranberries, blueberries, currants, OR chopped dried apricots
1. Combine flour, cornmeal, baking powder and salt in a medium bowl and mix together thoroughly with a whisk or a fork. Set aside.
2. Beat butter and sugar in a large bowl with an electric mixer until blended. Add eggs, vanilla and lemon peel and beat until light and fluffy.
3. Add flour mixture, stirring until all ingredients are moistened.
4. Add dried fruit, mixing with your hands if necessary. Shape dough into a 12"x2" log and place on a cookie sheet lined with parchment paper.
5. Bake in the middle of a pre-heated 350̊ oven 35 to 40 minutes, or until lightly browned and cracked on top. Cool 5 to 10 minutes.
6. Transfer loaf carefully to a cutting board. Using a long serrated knife, cut loaf on the diagonal into slices about 3/8"-wide. Lay slices, cut side down, on cookie sheet.
7. Bake about 10 minutes or until cookies are barely beginning to brown at edges.
8. Set pan on a rack. Cool cookies completely before stacking or storing. May be stored, airtight, for at least 2 weeks. Makes about 30 biscotti.
Notes: the batter is very soft and I spoon it into a log and shape it with a spatula to about 12" or 13" x 2-1/2" or 3". The dough spreads to about 5" wide while cooking. I slice the biscotti about 1/2" thick. I regularly double the amount of lemon peel. I have been known to add 1/2 tsp baking soda, 1 Tbs lemon juice and 1/4 cup flour successfully to the dough. For my own tastes, I much prefer dried cherries or cranberries in this recipe (I find raisins too sweet in it). It generally bakes in about 30 minutes in my oven at 350̊, plus another 15 minutes, after slicing, standing up on the cookie sheet.