I dream to cook these cocktails for my friends and treat them.

"Cognac with Champagne"
Cognac 40 milliliters, lemon juice 10 milliliters, sugary syrup, champagne 100 milliliters, ice. Mix Cognac, lemon juice, sugary syrup and ice. Pour out into champagne flute and add champagne.

"Pomegranate Juice with Champagne"
Cognac 20 milliliters, pomegranate juice 20 milliliters, lemon juice 40 milliliters, champagne 60 milliliters, ice. Mix cognac and juices in champagne flute with ice, add champagne.

You should drink cooled sparkling cocktail. Sometimes you can use powdered sugar for cocktails to sugar cocktails. Powdered sugar and water together will make froth.