Preheat the oven to 350°F (180°C) and line a 10-inch (25 ½ cm) tart pan with a removable bottom with the pate sucree crust. Prick the bottom all over with a skewer and refrigerate for 20 minutes.

Line the crust with parchment paper and pie weights and bake for 20 minutes, then remove the paper and weights and continue baking until the bottom is pale golden, about 10 more minutes. Remove from the oven and reduce the temperature to 325°F (165°C).

Place a medium heatproof bowl with a fine mesh sieve on top next to the stove.

In a large saucepan, whisk together the eggs, yolks, sugar and salt until smooth, then whisk in the orange and lemon juice.

Cook over medium-low heat, stirring constantly, until the mixture begins to thicken enough to coat the back of a spoon, about 6-8 minutes.

Immediately pour through the sieve into the heatproof bowl.

Stir in the butter and orange zest until the butter has melted, then pour this curd into your prepared tart shell.

Place on a rimmed baking dish to catch any drippings and bake for 35-45 minutes, until the edges are slightly puffed and set and the center is thick but still a little jiggly.

Let cool at room temperature for an hour, then transfer to the refrigerator to cool completely, about 3 hours.

Before serving, garnish with some piped whipped cream and orange slices if you wish.

Store leftovers in an airtight container in the refrigerator for up to 2 days.