Step 1

Heat water in the bottom pot of your double boiler until it comes to a boil. Reduce the temperature to medium.

Step 2

Place the egg yolks, lemon juice, allulose, lemon zest and salt in the top pot of the double boiler (or in a heat-safe bowl set on top of the pot of boiling water to make your own double boiler).

Step 3

Whisk the ingredients together and cook the mixture for 10-12 minutes. The liquid will turn slightly frothy, then a more pale yellow color. It will thicken toward the end of the 10 minutes- hang in there and keep whisking the curd gently. It is ready when it is the consistency of gravy or hollandaise sauce.

Step 4

Carefully remove the top pot (or bowl) from the heat and immediately fold in the softened butter. If using olive oil, drizzle in one tablespoon at a time, whisking it into the mixture to combine.

Step 5

Pour the lemon curd into a heat-proof glass jar. Allow the curd to cool to room temperature. Store in the refrigerator.