Combine 100 ml of the milk with the cornflour in a large bowl and whisk until smooth. Sprinkle in the saffron and set aside.
Place remaining milk and cardamom pods in a frying pan or wide-based, shallow saucepan over medium-high heat. Bring to the boil, occasionally stirring and scraping the base and sides of the pan. Once it reaches boiling point, continue cooking for 15 minutes, stirring just enough to stop the milk from boiling over or scalding, until reduced by about half (700 ml).
Strain, discarding cardamom pods, then whisk the hot milk mixture into the reserved saffron milk mixture. Transfer to a clean pan over high heat and bring to the boil, stirring constantly. Reduce the heat to low, stir in the sugar, pistachios, and honey, and cook for a further 2 minutes.
Transfer to a bowl and cover the surface with plastic wrap with a few holes spiked into it. Cool mixture to room temperature, then pour into 4 individual moulds or a single mould. Cover each surface with plastic wrap, then freeze for at least 6 hours or overnight. Transfer the kulfi to the fridge for 30 minutes to soften before serving.
Dip the base of the moulds into hot water and then turn kulfi out onto serving plates. Serve scattered with extra pistachios and drizzled with the extra honey.