Reddit mentions of HERSHEY'S Natural Unsweetened 100% Cocoa, Baking supplies and Beverage Mix Gluten Free, 8 Ounce Can (Pack of 6)

The very best chocolate cake I've ever eaten was first made and presented by my baking bestie. When I fell in love and asked for the recipe, she tossed the container of Hershey's baking cocoa at me. Not only is the recipe LITERALLY on the back, the frosting calls for MELTED butter, so both my sweet tooth and lazy ass are happy!

https://www.amazon.com/HERSHEYS-Cocoa-Natural-Unsweetened-Cacao/dp/B001EQ5AHW

All natural-process (opposed to the alkali/dutch process), unsweetened, 100% cacao powders should be nutritionally comparable to each other (with some exceptions depending on percent of non-fat cocoa solids, see below), the only differences will be in taste, organic status, and price. There's also some minor variations in the micronutrients based on growing region but I can't tell you which regions are better (and this is true of all foods too). You can probably divide iron%DV by calories as a simple heuristic to try to determine which cacao comes from a more fertile/mineral-rich growing region but this test probably won't give you the entire story since iron might be high and other nutrients low in one region and vice versa.

Just follow these general rules:

• Look for a product that is made with the 'natural' or non-alkaline method opposed to the 'dutch' or alkaline method.
  
  
• Make sure it is made from nearly-100% non-fat cocoa solids (NFCS). You can determine this by looking at the fat content of the product. It should be less than about 2-3g per TBSP. Cocoa powder that is truly made from 100% NFCS will have 0g fat per TBSP but I'm not aware of any products on the market that are 100% NFCS. Hershey's is the lowest at .5g per TBSP. Most of the nutrients in cocoa comes from the non-fat portion so the lower the fat content the more nutrients per calorie/serving the product probably has.
  
  
• Sugar content should be 0g per TBSP and "cocoa" should be the only ingredient on the label.
  
  
• With the above in mind then just pick something you like the taste of and pick an organic product if that matters to you.
  
  Some examples:
  
  Hershey's Natural Unsweetened 100% Cocoa is probably the best in terms of nutrients AND flavor per cost at only ~$3 per pound (locally, don't buy online). It has 0.2 %DV-iron per calorie. American Test Kitchen gave this chocolate their highest ranking in the supermarket category for flavor.
  
  Ghirardelli's 100% unsweetened cocoa is probably the best in terms of total micronutrients based on the iron/calorie test, but a lot more expensive at ~$6-9 per pound (much more online, but local stores will sell this for this price). It has 0.75 %dv-iron per calorie, one of the highest iron-content cocao powders that i've seen. American Test Kitchen also liked this one as well.
  
  All of the "raw" and organic products marketed towards the new-ager crowd will be nutritionally comparable to even the incredibly cheap Hershey's chocolate but will cost 3-5 times more. Also most of these are never made with anywhere close to 100% NFCS. They are always cut with cocoa butter, even Trader Joe's cocoa powder is cut with cocoa butter.
  
  
  
  
  
  

Hershey's 100% Cocoa Powder and a handful of almonds.

Sometimes I'll make it really thick, other times I'll put so much water in the oats it's almost like a soup. Depends on the mood.

Pricewise it isn't that awful:

• Healthworks
  
  
• Hershey's
  
  REgarding box mixes; You can also get them without so many nasty additives...