Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a medium bowl, whisk together the gluten-free flour blend, baking powder, and salt. Set aside.
In a large bowl, cream the softened butter and sugar together until light and fluffy. Beat in the eggs one at a time, then mix in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Fold in the chocolate chips. The dough will be stiff.
Turn the dough out onto a lightly floured surface (use extra gluten-free flour if needed). Form the dough into a log about 10 inches long and 2 inches wide.
Place the log on the prepared baking sheet. Bake for 25 to 30 minutes, or until the log is firm and lightly golden brown.
Remove the log from the oven and let it cool on the baking sheet for 10 minutes.
Reduce the oven temperature to 300°F (150°C).
Using a serrated knife, carefully slice the log diagonally into 1/2-inch thick slices.
Lay the slices cut-side down on the baking sheet.
Bake for another 10 to 15 minutes per side, flipping halfway through, until the biscotti are dry and crisp.
Cool completely on a wire rack before serving or storing.
Notes
If your gluten-free flour blend does not contain xanthan gum, add 1/2 teaspoon to the dry ingredients to help bind the dough.
For a dairy-free option, substitute the butter with a firm dairy-free butter stick.
If you prefer, substitute 1/2 cup of the chocolate chips with chopped almonds or pecans.
Store cooled biscotti in an airtight container at room temperature for up to one week.