Bring the cream to a simmer in a saucepan and remove from heat. Do not boil or the cream may curdle.
Add the lemon zest, cover and let sit while preparing the egg yolk mixture.
Beat egg yolks and ½ cup sugar in a large bowl for 1 minute. Add the lemon juice and beat another 30 seconds.
Temper the egg yolks by adding a small amount of the cream into the egg yolk mixture while beating continuously. Continue adding the cream a little at a time until fully combined.
Pour the mixture into 6 ramekins and place in a large baking dish.
Fill the baking dish with boiling water and bake for 30-35 minutes. The ramekins should be slightly jiggly in the middle when done.
Let cool for 15-20 minutes. Place in the fridge and let chill for 3-4 hours.
Sprinkle each ramekin with 1 tbsp. of sugar, and use a kitchen torch to caramelize (See note below).
Notes
Cook's Tips:
If your eggs are not room temperature, you can place them in a bowl of warm water for about 10-15 minutes to warm to room temperature.
Save the egg whites and store in the fridge for up to 1 week. They can be used in other recipes like this Chocolate Souffle.
Make sure to add the hot cream mixture into the egg yolk mixture VERY SLOWLY and just a little at a time while constantly whisking to endure you don't cook the eggs.
A broiler can be used if you don't have a blowtorch, but make sure it gets VERY hot before you put the sugar coated custards in. They should be very close to the heat source and should be left in for only 30 seconds to 1 minute max. Otherwise the custard will melt.
When making ahead, cover the custard in plastic wrap when storing in the fridge.