Leaves are GOLD for the compost pile. But yes balance is important.

I grew the best cabbages ever this year. I've been making cabbage pancakes which is 1 cup of flour, q egg, water into a batter (also some cornflour optional, say 1/4 cup) , lots of spring onions and chopped cabbage, a can of tuna and a handful of grated cheese. Form into a pancake and fry 5 minutes each side... So good. We like ours with chilli and soy sauce. A bit like a Korean vegetable pancake.