Preheat the oven to 350°F (175°C) fan or 360°F (180°C) conventional. Grease and line the bottom of an 8-inch (20 cm) round cake pan with parchment paper (baking paper)
In a large bowl, whisk together the eggs and sugar until light and slightly frothy (about 1 minute by hand).
Add the oil, orange zest, orange juice, and vanilla extract. Whisk to combine.
Fold in the almond flour, baking powder, and salt until smooth and no dry streaks remain.
If using chopped almonds, fold them in. Pour the batter into the prepared pan and smooth the top.
Bake for 30–35 minutes, or until the top is golden and a skewer inserted in the center comes out clean.
Dome with foil if browning too quickly. Especially near the 15 -20 minute mark.
Let the cake cool in the pan for 10–15 minutes, then turn out onto a wire rack to cool completely.