Cook the beets (recommend doing this in advance): Preheat oven to 400F. Wrap beets loosely in aluminum foil and roast for about an hour, or until can be pierced easily with a knife. Cool, peel, and puree in a blender until smooth
Preheat oven to 350F. Prepare 9x5 loaf pan.
Whisk together dry ingredients.
In a bowl, whisk together the beet puree with zucchini, eggs, milk. Stir in dry mixture.
Fold in chopped walnuts.
Bake for an hour, or until inserted toothpick comes out clean.
It’s super important that you remove the bread from pan as soon as you take it out from the oven. Otherwise it will become very moist and soggy. Cool on a wire rack. Wait until it’s completely cool (at least 30 minutes) before slicing.
Notes
If it still looks wet, don’t worry! Everything is cooked through. You just need to give it some time and it will firm up.