Preheat the oven to 350°F (180°C). Line a baking sheet with parchment paper or a silicone mat and set aside.
Sift all-purpose flour, chickpea flour, semolina, and salt together, whisk well, and set aside.
In a mixing bowl, whisk together Ghee and icing sugar until the mixture is light, fluffy, and pale in color. Add cardamom powder and vanilla, whisk until well combined.
To the wet mixture, add the dry ingredients and mix gently, first with a spatula, then with your hands, until a very soft, smooth dough forms.
Do not overmix or knead the dough. The dough will be easy to form and should be very soft but not sticky.
Scoop the dough and form equally sized balls. I used a very small ice cream scoop to make balls of dough, approximately 1½ tbsp. I could make 18 balls.
Flatten each ball slightly and place them on a baking sheet. Keep a good distance between each ball, as the Nan Khatai will spread during baking.
Make an indent in the center of each ball with your finger or thumb, and place chopped pistachio on it.
Bake the NanKhatai for 14-16 minutes or until the bottom is lightly golden. Keep an eye on Nan Khatai after 10 minutes of baking time, as each oven is different.
Remove NanKhatai biscuits from the oven, let them cool on the baking tray for 5 minutes, and then transfer them to the cooling rack.
Let NanKhatai cool completely, and then store them in an airtight container.