Found this via Jeffery Morgenthaler's blog: http://www.jeffreymorgenthaler.com/2012/i-make-the-best-amaretto-sour-in-the-world/
Even without top shelf ingredients this is an amazing cocktail. The nose is dominated by the almond liqueur, but the almond and lemon flavors work off each other very well. The rye does a good job bringing it all together.
1 1/2 oz amaretto liqueur
3/4 oz cask strength bourbon
1 oz lemon juice
1 tsp 2:1 simple syrup
1/2 oz egg white
Dry shake to emulsify. Shake with ice and strain over fresh ice in an old fashioned glass or a cocktail coup.