Preheat oven to 400°F (200°C). Butter and line cake pan or line muffin tins. Whisk together flour and baking powder. Beat egg yolks and sugar until thick and lemon yellow. Add orange juice and flour mixture; then mix in carrots and hazelnut meal. Mix eggs whites until firm, then fold them in. Bake 25min for cupcakes, 35min for cake.