I’m loving this one right now:

Sidecar
(this is how I make it but feel free to work on the balance until it’s to your liking)

1 ½ oz. Cognac (something like Martell VS)
¾ oz. Triple Sec (like Hiram Walker)
¾ oz. Fresh Lemon Juice

Shake over ice and serve in a chilled cocktail glass. Garnish with a lemon slice (which I like to dip in sugar first). Cheers!