Step 1

With the rack in the middle position, preheat the oven to 250°F (120°C). Butter an 8-inch (20 cm) square baking pan and line with parchment paper, letting it hang over two sides.

Step 2

In a small food processor, finely chop the almonds and pistachios with the cornstarch.

Step 3

In a bowl, whisk the egg white and cream of tartar with an electric mixer until foamy. Gradually add the sugar, while whisking, until stiff peaks form. Fold in the nut mixture with a spatula or whisk. Spread evenly in the baking pan.

Step 4

Bake for 35 minutes. Let cool completely in the pan. Pass a thin blade between the pan and the dacquoise. Unmould and break into pieces.

Step 5

Meanwhile, place the chocolate and cardamom in a bowl.

Step 6

In a small pot, bring the cream to a boil. Pour over the chocolate and let sit for 1 minute without stirring. Whisk the mixture until smooth. Cover and refrigerate for 2 hours. The ganache will keep for 1 week in an airtight container in the refrigerator.

Step 7

In a separate small pot, bring the orange juice and sugar to a boil. Let reduce by half. The syrup will keep for 1 week in an airtight container in the refrigerator.

Step 8

On a work surface, supreme the oranges by removing the skin, pith and membrane with a knife and divide into skinless sections.

Step 9

On each plate, place a quenelle of ganache, about 3 tbsp (45 ml) in size. Add a few segments of orange and a few pieces of dacquoise. Drizzle with orange syrup. Sprinkle with chopped pistachios, if desired.