Preheat oven to 350°F/175°C. Line a baking sheet with parchment paper. Set aside.
In a large bowl, mix together flour, sugar, baking powder, salt, cinnamon, and orange zest. Stir in dried cranberries. Set aside.
In another medium bowl mixed together eggs, butter, orange juice, and liqueur. Add the mixture to the flour mixture, and mix with a spatula until combined and a dough is formed. If dough is too sticky, add additional flour, 1 tablespoon at a time, until it no longer sticks to your hands.
Transfer dough into a lightly floured surface, and form into a ball. Divide into 2 equal pieces. Shape each half into a rectangle the size of 8x3-inch (20x8cm). Place them on the baking sheet, spacing them 4-inch (10cm) apart.
Bake for 25 minutes or until firm to the touch, and the top begins to crack. Remove from the oven without turning off the heat. Allow biscotti to cool on a wire rack for 20-30 minutes. Cut each log into ½-inch thick slices (they can be thicker or thinner, so make them any size you want), using a sharp knife. Place slices cut-side up on the baking sheet in one layer. Place in the oven and bake for 10 minutes, then turn slices over and bake the other side for 10 minutes. Allow cookies to cool completely on a wire rack.
Drizzle biscotti with melted white chocolate, if desired, using a spoon or a piping bag.
Store cookies in an airtight container at room temperature for up to a month.