Peel the carrots and grate them coarsely. Cream 125 g butter, 100 g sugar and vanilla sugar with the whisk of the hand mixer. Stir in eggs one after the other. Mix flour and baking powder and stir in alternately with the carrots.
Pour into a greased box mould (11 x 26 cm; 1.5 litre capacity) sprinkled with flour. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 45 minutes.
Remove and let it cool down on a cake rack.
Wash the oranges, grate them dry and peel them in zests. Halve 1 orange, squeeze the juice. Caramelise 25 g sugar in a small saucepan, add 5 tbsp. orange juice and simmer at low heat until the caramel has dissolved.
Add orange zest and remove from heat.
Mix 100 g butter and icing sugar until creamy. Add cream cheese and cream and whip until creamy. Stir in 2/3 of the orange zest. Carefully remove the cake from the tin and cut horizontally 2 times.
Place the lower base on a plate and spread 1/3 of the cream cheese mixture on top. Place the middle base on top and spread 1/3 of the cream cheese mixture on top. Place the upper base on top and spread the rest of the cream cheese mixture on top.
Spread the rest of the orange zest on top. Chill for at least 1 hour.