Pistachio White Chocolate Chip Biscotti

unsalted butter, melted

vegetable or canola oil

large egg, room temperature

and ½ teaspoons vanilla extract

granulated sugar

and ¾ cup + 1 Tablespoon all-purpose flour

baking powder

salt

roasted salted pistachios, finely chopped (about ¾ cup)*

white chocolate chips

large egg beaten with 1 Tablespoon water