Preheat the oven to 80c/175f.
Add the desiccated coconut and your chosen colouring powder to a bowl and mix until evenly coated. Add 1–2 teaspoons of water and stir again. You want the coconut just lightly damp so the colour sticks, not wet or clumpy.
Spread the mixture in a thin, even layer on a lined baking tray. Repeat with remaining colours if making a large multi-coloured sprinkle batch (we do 5 colours across 2 trays).
Bake without a fan for 1 to 1½ hours, until fully dry. Gently stir every 20–30 minutes, using a fork to move the edges toward the centre and break up any clumps without pressing or squashing the texture.
Once dry and crisp, allow the sprinkles to cool completely on the tray, before storing in an airtight container.
Once fully dry, store in an airtight container at room temperature for up to 2 months, or up to 6 months in the fridge or freezer. If the sprinkles soften due to humidity or incomplete drying, simply return them to a low oven for 10 minutes to refresh.
