Preheat oven to 180°C. Grease and line the base of a round 20cm (base measurement) springform pan with baking paper.
Use an electric mixer to whisk the eggs and sugar in a bowl until thick and pale. Add the oil and liqueur and whisk until just incorporated. Add flour, hazelnut meal, baking powder and rind and use a metal spoon to gently fold until just combined. Pour mixture into the prepared pan. Sprinkle the hazelnuts evenly over the top. Bake for 45 minutes or until a skewer inserted in the centre comes out clean.