1. Zest the oranges first, then squeeze the juice and set both aside.

2. In a medium heatproof bowl or saucepan, whisk together the orange juice, orange zest, sugar, egg yolks, whole eggs, cornstarch, and salt until smooth.

3. Place the bowl over a pan of gently simmering water or set the saucepan over low heat.

4. Cook the mixture slowly, stirring constantly, until it thickens enough to coat the back of a spoon.

5. Remove from the heat and add the butter one piece at a time, stirring until fully melted and incorporated.

6. Stir in the vanilla extract until the curd is glossy and smooth.

7. Strain the orange curd through a fine-mesh sieve into a clean bowl or jar.

8. Press plastic wrap directly onto the surface and chill until fully cooled and set.

9. Serve cold as a spread, topping, or filling.