I'm surprised the original Valencia is not on the site. It's basically the same drink but without Champagne and is delicious. 45 ml apricot, 22.5 ml orange juice, 4 dashes orange bitters shaken with ice.
This is perfect for lunch or brunch. The apricot liqueur add a subtle undertone to which is primarily a champaign and orange cocktail. Would highly recommend.
Having found The French 75 I went looking for an orange "equivalent" on Simon Difford's excellent website and found this; I even bought the orange bitters especially or it. It's a good cocktail and tastes nicely orangey, not particularly of apricots. Maybe a fraction too sweet for me so I've scored down a bit. I prefer the French 75 over this when I fancy a "fizz-based" cocktail.