Chocolate Chip Rainbow Biscotti

Name: Chocolate Chip Rainbow Biscotti
Prep time: 40 min
Cook time: 40 min
Total time: 1 h 20 min
Cuisine: European, Italian, Mediterranean
Ingredients: 256 grams all purpose flour (2 cups), plus more for dusting countertop; 100 grams granulated sugar (1/2 cup); 1 teaspoon baking powder; 1/4 teaspoon fine sea salt; 45 grams unsalted butter, cold and cubed (3 tablespoons; 1 1/2 ounces); 2 large eggs; 1 teaspoon vanilla extract; 100 grams semi-sweet chocolate chips (1/2 cup; 3 1/2 ounces); 1 egg white, lightly beaten; 30 grams rainbow nonpareils (2 tablespoons), plus more for coating*