To make the spiced butter, scoop the softened butter into a bowl and add the demerara sugar. Beat together with electric beaters until smoothly combined.
Add all the spices and beat again. Scoop into a tub, seal and store in the fridge until needed. The butter will keep in the fridge for up to 4 weeks.
Pour the apple and lemon juices into a saucepan over a medium heat. Cover with a lid and gently warm for 5–6 minutes until steaming hot. Scoop the spiced butter into the pan and stir until dissolved (see above for instructions if you are not serving all at once). Ladle the buttered apple juice into mugs or heatproof glasses and grate over a little extra nutmeg to serve.
