Create-Your-Own Biscotti!

I am making biscotti for our Fall Festival coffeehouse this week, and this seems to be one of those recipes that you can't seem to mess up (the best kind, in my opinion).

Create-Your-Own Biscotti
(adapted from The Chocolate Cake Doctor)
1 box any flavor cake mix
1 cup flour
1 stick butter, melted
2 large eggs
½ tsp flavoring (vanilla, almond, etc.)
¼ to ½ cup mix-ins (chips, nuts, dried fruit, etc., chopped)

Preheat oven to 350F. Mix all ingredients together (a stand mixer makes short work of this, but you could also use a hand mixer), about 3-4 minutes. Mixture will be thick and form a ball (you may have to use your hands to get it all the way into a ball).
Pat dough out on a cookie sheet (you can use parchment if you want) into a rectangle about ½ inch thick and about 6 inches wide, mounded a little in the middle. Bake at 350F for about 30 minutes, until a toothpick in the middle comes out clean. Slice on the diagonal, about ½-1 inch thick slices, directly on the cookie sheet (if you move the dough, it will crack). Turn the slices carefully onto their sides. Put the cookie sheet back in the oven and bake for another 10 minutes. Then turn the oven off and let the biscotti sit in the closed oven for at least 35 minutes, and then cool completely and dip in chocolate, if desired.

Successful combinations so far:
Yellow cake mix, almond extract, almonds, dried cranberries, white chocolate chips
Chocolate cake mix, vanilla extract, chocolate chips, dried cranberries & blueberries
Chocolate cake mix, dark & white chocolate chips
Chocolate cake mix, vanilla & spices (cinnamon, nutmeg, ginger)
I'm going to try chocolate with peppermint chips at Christmastime!