Fill a saucepan with 2 inches of water and heat it over medium-low until it begins to simmer gently.

In a large heat-proof bowl, combine eggs (or egg yolks), granulated sugar, canned pineapple juice, cornstarch, and fine salt. Whisk until completely smooth.

Place the bowl over the simmering water, continuously whisking for about 5 to 8 minutes until thickened and resembling a custard-like texture.

Remove the bowl from heat and add unsalted butter, stirring until it melts completely.

Transfer pineapple curd into an airtight container, cool to room temperature, then seal. Refrigerate for up to 2 weeks or freeze for up to a month.