Add the Arborio rice, whole milk, coconut milk, brown sugar, cinnamon, cardamom, ginger, cloves, vanilla extract, and salt to the slow cooker.
Stir the mixture well to dissolve the sugar and distribute the spices evenly.
Cover and cook on low for 4 hours, stirring once halfway through to prevent the rice from sticking.
Check the consistency at the end of cooking. If the pudding seems too thick, stir in a splash of milk to loosen it.
Spoon into bowls and top each serving with chopped pistachios.