I was curious how different a cake made with American and European blueberries tastes and looks. I made a sponge cake base and a dairy-free filling with my homemade vegan cream cheese substitute and homemade marshmallows.
For each half I used the same amount of pureed blueberries (Vaccinium corymbosum) and bilberries (whortleberries, Vaccinium myrtillus). Blueberries have white flesh, while bilberries have dark red flesh. As expected, the bilberries dyed the filling purple, whereas the blueberry filling is just pale lavender. The bilberry filling tastes strongly of blueberries, and the blueberry filling has just a hint of blueberry flavor.
Bilberries can also be used to dye fabric.