Wash and trim the rhubarb, chop into 1-inch pieces, and place in a saucepan with a small splash of water. Cook over medium heat for 5-7 minutes until soft, then blend into a smooth puree.

In a mixing bowl, crack the eggs and separate the yolks from the whites. Whisk together the egg yolks and whole egg until pale and slightly frothy.

Gradually pour the warm rhubarb puree into the egg mixture, whisking continuously to avoid scrambling.

Return the mixture to the saucepan and cook over low to medium-low heat, stirring constantly for about 5-7 minutes until it thickens to 170-175°F.

Remove from heat and add the butter, whisking until fully melted and incorporated.

Strain the curd through a fine mesh sieve into a bowl for a smoother texture.

Pour into a clean jar or airtight container, let cool to room temperature, then refrigerate for up to 7-10 days.