Bring blackberries and lemon juice to boil.
Crush blackberries with fork or masher. Let it boil till juicy.
Sieve blackberry juice in a pot.
Add sugar to blackberry juice and bring to boil.
Mix the egg and egg yolks in a separate bowl.
Pour blackberry juice slowly to the eggs while whisking.
Pour mixture back in the pot and heat on small fire for about 5 minutes until it thickens.
Stir in pieces of butter.
Fill the hot Blackberry Curd in a clean jar.
Stored in fridge lasts about 2 weeks.