01 - In a medium heatproof bowl, whisk together the eggs, egg yolks, sugar, pink lemon juice, and zest until completely smooth and well combined.
02 - Place the bowl over a saucepan of simmering water, ensuring the bowl bottom does not touch the water surface to create a gentle, indirect heat source.
03 - Cook the mixture, whisking continuously to prevent curdling, for 8-10 minutes until the curd thickens noticeably and coats the back of a spoon (reaches approximately 170°F).
04 - Remove from heat immediately. Whisk in the butter pieces one at a time, allowing each piece to fully melt before adding the next, until the curd becomes silky and emulsified.
05 - If using, stir in raspberry juice or natural pink food coloring to achieve the desired blush hue, mixing gently to incorporate evenly.
06 - Pour the curd through a fine-mesh sieve into a clean bowl to remove the zest and any cooked egg bits, ensuring a perfectly smooth texture.
07 - Let the curd cool to room temperature, then transfer to sterilized jars. Refrigerate for at least 2 hours to set completely. Store chilled for up to 2 weeks.