Preheat oven to 350. Line a baking sheet with a silicon baking sheet or use parchment paper and set aside.
In a small bowl, whisk together the salt, baking powder, and flour. Set aside.
In the bowl of a stand mixer (or use a hand mixer), combine butter and sugar until creamy.
Add in the vanilla, and eggs (one at a time). Beat well after each egg.
Add in the flour, a little at a time, beating until mixture is smooth.
By hand, stir in white chocolate chips.
Lightly dust lined baking sheet with a small amount of flour. Transfer dough to baking sheet and shape into a log about 14 inches long and about 2 inches wide.
Bake for 25 minutes. Remove from the oven and let stand for about 20 -25 minutes.
About 5 minutes prior to cutting the biscotti log, gently brush with a sprinkle with water, be sure to reach the sides of the biscotti.
Reduce oven temperature to 325.
Patiently wait another 5 minutes before slicing biscotti into 3/4 inch slices.
Stand biscotti upright and bake for 25 more minutes. Remove and let cool on baking sheet.