Preheat the oven to 325°F(165°C). Line baking sheet with parchment paper.
If your cranberries are too dry and not soft, place the cranberries into a bowl and pour boiled water on top to soften them. You can keep them 10 minutes in boiled water. During this time, continue with the next steps. After 10 minures drain and blot them with a paper towel. This whole step is optional. If the cranberries are not too dry simply skip this step or if needed depending on the cranberries, keep them in boiled water for less time.
Place the flour, baking powder and salt if using in a medium bowl and stir. Set aside.
Mix the sugar and orange zest in a medium bowl. Either use a fork or rub with your fingers.
Add the eggs and stir with a whisk for a couple of seconds until combined.
Mix in the butter and vanilla extract.
Add the flour mixture in 2 batches and stir with a spoon until barely combined. You can first use a whisk to combine but you need to use a spoon after the second batch. Stir in the cranberries evenly.
Divide the dough in half and turn each dough into a 7.5 inch (19 cm) long, 3.15 inch (8) cm wide log. The dough is easy to work with but somehow if you find it sticky(let's say you used less flour), flour your hands and try to give the log shape.
Bake for 30 minutes or until the top is lightly golden brown. (In my oven it becomes slightly lightly brown at 24 minutes. I keep baking 6 more minutes.)
Remove the baking sheet from the oven (don’t turn off the oven), let it cool for almost 10 minutes and cut each log at an angle into 0.6 inch (1.5 cm) slices. Cut the slices very gently as they are soft at this moment.
Place each slice cut side down onto the same baking sheet and let them bake for 14 minutes, flip them halfway. Let them cool completely cool to let them be crunchy.