Preheat your oven to 350°F (175°C) and grease a loaf pan.

In a mixing bowl, whisk together the flour, baking powder, baking soda, and salt.

In a separate large bowl, cream the softened butter and sugar until it turns light and fluffy.

One at a time, add the eggs, incorporating them well after each addition. Mix in the vanilla extract and mascarpone until smooth.

Gradually fold the dry ingredients into the wet ingredients, being cautious not to overmix. Gently fold in the chopped pistachios.

Pour the batter into the prepared loaf pan, smoothing the top with a spatula.

Bake for 60-70 minutes or until a toothpick inserted in the center comes out clean.

Allow the loaf to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.