In a medium saucepan, over medium-high heat, heat cream, lemongrass, vanilla, just until bubbles begin to form around edge of saucepan.
Remove lemongrass stalks.
In a heat proof bowl, whisk egg yolks with sugar until pale
Pour heated cream mixture slowly into the beaten egg yolks, whisking as you pour.
Strain mixture through a sieve, and divide among 6 -6 ounce ramekins, or 8- 4ounce ramekins.
Bake at 325 degrees F (160 C) in water bath for 40-45 minutes, or just until set around edges. If custards are beginning to brown on top, cover loosely with foil.
Remove from water bath, cool and refrigerate for at least 2 hours prior to serving.
Sprinkle top of each ramekin with about 1 teaspoon sugar, shake gently to spread.
Using torch or quickly heating under broiler, carmelize tops until sugar bubbles and is amber in colour. Cool and serve.