Here are two of my favourite champagne cocktails, for the festive season:

Kir Royale

This always reminds me of Europe, where I drank it as an aperitif everywhere we ate.

30ml crème de cassis
100ml chilled brut champagne

Pour crème de cassis into a chilled champagne flute & top with chilled champagne.
Alternatively, you can pour the champagne first and then add the crème de cassis so it sits in the bottom of the glass.
Enjoy!

Passionate Affair

15ml passionfruit liqueur
10ml passionfruit in syrup
120ml chilled brut champagne

Combine passionfruit liqueur & passionfruit in a champagne flute. Top with chilled champagne.
You'll get drunk v. quickly after a couple of these!