Ingredients

• 2 cups of water
• 7 tablespoons of cornstarch
• 1 1/2 cups of granulated sugar
• 3 eggs - yolks only
• 1 lemon, juiced and zested
• 1 tablespoon of butter

Instructions

1. Prepare Ingredients: Juice and zest the lemon. Separate the egg yolks from the whites. Measure out all other ingredients.

2. Mix Cornstarch with Water: In a small bowl, mix the 7 tablespoons of cornstarch with 1/2 cup of water until smooth. Set aside.

3. Combine Remaining Ingredients: In a saucepan, combine 1 1/2 cups of water and 1 1/2 cups of granulated sugar. Add in the lemon zest and juice.

4. Cook Mixture: Place the saucepan over medium heat and bring the mixture to a boil, stirring constantly.

5. Thicken with Cornstarch Mixture: Once the mixture is boiling, slowly pour in the cornstarch mixture while stirring constantly.

6. Continue Cooking: Reduce the heat to low and continue cooking the mixture, stirring constantly, until it thickens. This should take about 2-3 minutes.

7. Temper Egg Yolks: In a small bowl, whisk the egg yolks.

8. Add Egg Yolks: Slowly add a small amount of the hot lemon mixture into the egg yolks, whisking constantly. This tempers the egg yolks and prevents them from curdling when added to the hot mixture.

9. Incorporate Egg Yolks into Mixture: Once tempered, pour the egg yolk mixture back into the saucepan with the rest of the lemon mixture, stirring constantly.

10. Add Butter: Continue to cook the mixture over low heat, stirring constantly, until it reaches a thick consistency, similar to pudding. This should take another 2-3 minutes.

11. Remove from Heat: Once the filling has thickened, remove the saucepan from the heat and let the filling cool slightly.