Place strawberries plus 2 Tbsp of water in a large saucepan over a medium heat. Cover and bring to the boiling point. Simmer for 5 minutes or until the strawberries become very soft.
Use a slotted spoon to transfer strawberries to mesh sieve. Place sieve over a clean, heatproof bowl and use the back of a spoon to push strawberries through the mesh sieve. Keep pressing the pull through. Add the pulp into the strained strawberry liquid.
Place the heatproof bowl over a saucepan of simmering water on medium heat. Make sure the bowl fits snugly and that the water doesn't touch the bottom of the bowl. Add the sugar, beaten eggs and butter to the bowl and stir with a wooden spoon until the butter melts. Continue to stir constantly for about 10 minutes.
Turn the heat up and continue to stir for another 10 minutes. It's important to keep stirring otherwise the mixture could curdle.
Stir for another few minutes or until the mixture thickens. Turn off the heat and stir again. Carefully pour mixture into hot sterilized jars and seal.