I have never tried it but my sister gave me a recipe for a chocolate cake made with milk chocolate and cocoa. You might give it a try, it's an Austrian recipe.
400g all purpose flour
3 eggs, room temp, divided
125g butter, soft
300g powdered sugar
1 tsp vanilla extract
70g milk chocolate, finely grated
375ml milk (3.5% fat)
3 tsp baking powder
(optinal: cherry jam for glazing)
1. cream butter. gradually add sugar, egg yolks, cocoa, milk chocolate and vanilla extract.
2. add 3 tbsp flour and as soon as it is absorbed at 1-2tbsp milk. proceed till finishing milk and flour completely.
3. whisk egg whites and carefully fold under the dough.
4. add baking powder.
5. bake for 30-45min at180°C/°F350 (don't preheat oven!)
6. cool completely inside the closed oven.
7. glaze with jam
I hope you understand everything as I am not a native speaker. Let me know if you tried and how it went :)