Rinse the cranberries under cold water, discarding any soft or blemished ones. Place them in a medium saucepan and pour in 1/2 cup of water. Bring to a boil over medium heat. Once boiling, reduce the heat and allow the cranberries to simmer until they burst and soften—about 10 minutes.

Using a fine-mesh sieve, strain the cranberry mixture to separate the liquid from the skins. Press down on the solids to extract as much juice as possible. You should have about 1 cup of cranberry juice.

In a different bowl, whisk together the sugar and eggs until fully combined. Gradually stir in the cranberry juice and lemon juice.

Pour the mixture back into the saucepan and place it over low to medium heat. Cook while stirring constantly until the mixture thickens and coats the back of a spoon—this should take about 8-10 minutes. Do not let it boil.

Remove the saucepan from the heat and whisk in the softened butter until melted and well combined.

Transfer the cranberry curd into sterilized jars and let it cool to room temperature. Seal them and store in the fridge for up to two weeks.