For candied cumquats, place cumquats in a heatproof bowl, cover with boiling water and stand until cool. Drain and repeat twice more. Combine sugar, ginger and 1¼ cups water in a saucepan and stir over medium-high heat until sugar dissolves. Add cumquats, bring to the boil, then reduce heat to medium and simmer for 40-45 minutes or until fruit is translucent and liquid is syrupy. Candied cumquats can be made ahead and will keep, stored in an airtight container in the refrigerator, for up to 3 months.
Combine milk, honey and rind in a heavy-based saucepan and bring just to the boil over medium heat. Add semolina in a steady stream, and cook, stirring continuously, for 5-6 minutes or until thick and bubbling. Add butter, stir to combine, then divide among bowls, spoon over cumquats and syrup, scatter with pistachios and serve immediately.