Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper.

Cream together the softened butter and sugar until light and fluffy using an electric mixer.

Beat in the eggs one at a time, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.

Stir in the candied fruit and nuts, if using.

Divide the dough in half. On a lightly floured surface, roll each half into a long log, about 1 ½ inches in diameter. Place the logs onto the prepared baking sheets, leaving some space between them. Bake for 25-30 minutes, or until lightly golden brown.

Let the logs cool on the baking sheets for 10-15 minutes before transferring them to a wire rack to cool completely. Once cool, slice the logs diagonally into ½-inch thick slices.

Arrange the slices cut-side down on the baking sheets. Bake for another 8-10 minutes, or until lightly golden and crisp. Let the cookies cool completely on the wire rack. Once cool, dust with powdered sugar.