- 2 1/4 c. sugar
- 2 tsp. cornstarch
- 1 c. lime juice (4–5 limes)
- 4 large eggs
- 4 yolks
- 3/4 c. (1 1/2 sticks) unsalted butter
- In a heavy-bottomed saucepan, add sugar and cornstarch. Whisk to combine.
- Whisk in lime juice followed by the eggs and yolks.
- Add in the butter one tablespoon at a time.
- Cook on medium-high heat, whisking continuously.
- When the curd begins to thicken and bubble (or burp), whisk quickly for one minute.
- Pour curd through a fine-mesh sieve to remove any clumps into a bowl. Cover with plastic wrap and place in refrigerator to cool, about 3 hours. To speed up cooling process, place over a bowl of ice water in the fridge.
- Curd will last covered in fridge for about 2 weeks.
- For cupcakes, cut out a wedge, fill with curd, top with removed cake, and frost. For cakes, pipe a circle of icing around the inner edge of the bottom cake layer. Fill with curd, top with cake layer, and frost.
• Substitute lemon or orange for limes to change it up.
• Save remaining egg whites for the buttercream.