Lemon butter can be made up to 4 weeks ahead; store in refrigerator.
This recipe is unsuitable to freeze or microwave.
165g (3/4 cup) sugar
2 teaspoons grated lemon rind
125ml (1/2 cup) lemon juice
1/4 cup water
125g butter, chopped
Combine all ingredients in top half of double saucepan or in heatproof bowl stir constantly over simmering water until mixture thickly coats the back of a wooden spoon. Pour into hot sterilised jars; seal when cold.
Makes about 3 cups.