To make the orange sweet pastry, cream the butter and sugar together in a stand mixer until light and soft. Add the orange zest, egg yoks and 25ml/1fl oz water and mix again. Add the flour in three additions, mixing very briefly each time.
Bring the pastry together to form a flat disc, wrap with greaseproof paper and place in the fridge for an hour.
Preheat the oven to 190C/170C Fan/Gas 5.
Roll the pastry out on a clean surface to 2mm thick and line the tart rings, making sure the pastry is pushed into the edges. Trim the pastry leaving a 1in/2cm overhang. Line with scrunched up greaseproof paper and fill with baking beans and blind bake for 15 minutes, then remove the beans and paper and bake for a further 5 minutes until golden-brown.
To make the filling, melt the white chocolate in a bowl set over a pan of gently simmering water. Be very careful that the water doesn’t touch the bowl.
Place the champagne, orange juice and zest in a small pan and warm gently. Pour over the chocolate and whisk until completely smooth. Pour into the baked tart cases and place in the fridge for 1 hour. Put the rest of the ganache in a bowl and set in the fridge to make the snowballs.
To make the snowballs, roll the leftover ganache into various sized small snowballs and roll in icing sugar. Leave in the fridge until needed.
To make the snow, place the chocolate in the fridge, then blend in a food processor to form a small crumb, tip into a bowl and mix with some shimmer powder.
To make the snowflakes, melt the white chocolate in a bowl set over a pan of gently simmering water. Be very careful that the water doesn’t touch the bowl. Allow to cool to room temperature.
Fill a squeezy bottle or piping bag with the melted chocolate and cut the smallest possible hole in the top. Tape some baking paper to a tray or your work surface, and pipe your snowflakes onto them. Be creative and make different shapes and sizes.
To decorate, trim the excess pastry from the tart cases and slide off the rings. Pile the snow on top and dot the snowballs around. Top with the snowflakes and place on a cake stand. Serve at room temperature and cut with a hot, wet sharp knife.