I gave this cookie the name, “building block,” because the fillings can be modified to suit your taste. The versions below are nut-free. They are dairy-free if pareve white chocolate chips are used.
Ingredients:
2 ½ cups all-purpose flour
1 tsp. baking powder
½ tsp. salt
1 ½ cups granulated sugar
½ cup (1 stick) unsalted pareve margarine, room temperature
2 large eggs, room temperature
1 tsp. pure vanilla extract
1 cup white chocolate chips/semisweet chocolate chips
1 cup dried berries/toasted flaked coconut/toffee pieces
1 egg white
Directions:
Preheat oven to 350F. Line 2 baking sheets with parchment paper. Combine flour, baking powder and salt in medium bowl; whisk to blend.
In the bowl of an electric mixer fitted with the paddle attachment, beat margarine and sugar until light and fluffy. Add eggs, one at a time, followed by vanilla and beat until smooth.
Mix in flour mixture, then chips and berries/coconut/toffee. Cover the dough with plastic wrap for 2-24 hours.
Divide dough into 3-4 logs each approximately 6×2.5 inches (15x7cm) long. The logs will expand during baking.
Whisk egg white in small bowl until foamy; brush egg white glaze on top and sides of each log.
Bake logs until golden brown about 35 minutes.
Cool for 10 minutes, then slice logs on diagonal into ½-inch wide slices. Bake for 10 more minutes. Allow biscotti to cool. Makes approximately 40 biscotti.
The Science of Baking 