Chocolate Beet Muffins

I'm still working on things to make with this 10 lb bag of beets I bought. These muffins are very moist and not overly sweet. Two experts (read 2 friends who cook/bake quite a bit) weren't sure what the secret ingredient was. They thought maybe cherry or cranberry was in the mix, but not beets. I don't believe in hiding healthy stuff from kids or spouses who might be picky, but let them taste these first before telling them what's in it.

2 medium raw beets (250 g)
1 apple
2-3 tbsps chopped prunes (about 5-6)
2 tsp ground flax (optional)
1 tsp vanilla
2 eggs
1/3 cup brown sugar
1/4 tsp salt
1 1/2 tsps baking soda
1/4 cup vegetable oil
1/4 cup milk
1/2 cup cocoa
1 cup flour
1/3 cup whole wheat flour
1/2 cup chocolate chips

Wear gloves and brush the beets clean, then grate them, peel and all. Grate the apple with it's peel too. Mix together. I know, it looks gross!

Mix all dry ingredients together and toss in the prunes. I think dates or raisins would work well here too.
Mix the liquid ingredients together.

In a large bowl mix about 1/3 of each, dry and liquid, and continue adding until everything is incorporated. It looks a bit dry at first, but don't worry, it comes together.

Fold in the chocolate chips. The batter will be thick. Spoon it into muffin papers and bake at 375 F, 8-10 minutes for small muffins and 18-20 for large.