【Help me】How to make the beetroot color brighter when I bake cakes?

I baked beetroot and pear cake today. Recipe is posted on the previous page.

I am satisfied the taste of this awesome cake but I couldn't make the beautiful pink color of beetroot active when I baked.
How should I make it?

I know beetroot is easily affected by heat. So if I want to the pink color very active, I should make raw cake.
There are lots of beetroot cake recipes, especially with chocolate, and they look so good but most of them don't have beautiful color behind dark chocolate.