Wash the chana dal and soak it in a large bowl with plenty of water for 2 hours. Drain well.
Blend the soaked dal with 1 cup water until thick and smooth.
Line the air fryer tray with baking paper and spoon the dal mixture over it.
Air fry at 180°C for approximately 25 minutes.
During cooking, use 2 tablespoons ghee to brush the surface. Flip the mixture and brush with ghee again so it cooks and browns evenly.
Remove the cooked mixture and allow it to cool.
Break the cooked dal into pieces and grind until fine but slightly grainy.
Transfer the ground mixture to an air-fryer-safe pan. Add ¼ cup ghee and mix thoroughly.
Air fry at 170°C for 10 minutes.
In a bowl, combine 1½ cups powdered sugar and cardamom powder. Add ¾ cup hot water and stir until the sugar dissolves.
Pour the sugar mixture into the roasted chana dal mixture and combine thoroughly.
Air fry at 170°C for another 10 minutes, mixing during cooking if required.
Transfer the warm mixture to a tray and press it into an even layer.
Top with chopped pistachios and dried rose petals.
Allow the mohanthal to cool completely at room temperature before cutting.
Because the finished mohanthal is slightly crumbly, use a sharp knife and cut slowly and gently into squares or diamond-shaped pieces.