Preheat the oven to 170C/340F fan-forced.

Grease and line base and sides of a 24cm spring-form tin then dust lightly with flour (you can use gluten free flour to make it gluten free).

Place pecans and chocolate in food processor and grind in short, sharp burst until finely ground, being careful that it doesn't turn to paste. Set aside.

Beat the egg yolks and sugar with electric beaters for 4 mins until thick and pale. Gently mix in the butter and vanilla then stir in the pecan mixture until thoroughly combined.

In a separate bowl, whisk the egg whites with a pinch of salt until fluffy and holding their shape but not overly stiff. Whisk a quarter of the whites into the yolk mix then fold in the remaining whites gently but thoroughly.

Pour the batter into prepared pan and jiggle it lightly to settle it evenly.

Bake for 50 mins or until it begins to pull away from the sides of the pan and feels firm when you place the palm of your hand on the surface and wobble it gently.

Cool the cake in the pan for 10 mins then carefully inver onto the rack to cool completely.

To serve, dust with cocoa then serve with whipped cream. Store in an airtight container in the fridge for up to 1 week.