This is the recipe I use - it will freeze in ice cube trays.
25 heads of fragrant elderflowers, preferably picked when the sun is on them
1.5 kg sugar (the original recipe called for 2kg but I found that too sweet
2 litres water
2 large lemons, sliced
Put the water, sugar and lemons in a pan and heat gently, stirring, until the sugar as dissolved. Allow to cool then pour over the elderflower heads. Leave to stans for two days in a covered container then strain and bottle (seal loosely in case of fermentation!). Keep in the fridge and dilute with water as you would fruit squash. It's also very refreshing diluted with chilled sparkling mineral water, on a hot day in the garden
lottie
I made bottles of it last year and kept it in the fridge in the garage - and used it in all sorts of ways.
The elderflowers are not out fully yet here - except in next door's garden