Slice the butter into pats and set it in a bowl with a sieve over it.

In a small pot, add the blueberries, lemon zest and lemon juice. Cook on medium low heat for about 20 minutes, stirring as needed until most of the blueberries burst and are completely softened, having released their juices.

Strain this into a bowl to remove blueberry skin. You should have about 180g give or take of liquid. This is how much you need for the curd.

Pour the blueberry juice into the pot (use the same one as long as you’ve scraped it clean of bits) and add the sugar.

In a bowl, beat the eggs with the salt with a fork. Pour into the pot with the sugar and blueberry. Whisk to combine.

Cook over medium low heat, stirring constantly until thickened and temperature reaches 170 F.

Pour through the sieve over the butter. Stir until butter is melted and curd is smooth.

Store in the fridge in an airtight container. Curd should keep for about three weeks.