Preheat oven to 300°. Line a large cookie sheet with parchment or a silpat mat.
In large bowl, beat eggs and extract with hand mixer. Blend in sugar. Sift together flour, cocoa, baking soda, and salt. Mix to blend. Stir in chocolate chips.
Spoon batter into one long log down the center of parchment. Bake for 50 minutes.
Remove from oven. Leave oven set to 300°. Wait 5-10 minutes, then slice large cookie log crosswise into ½ inch slices.
Place slices on cookie sheets and bake for 25 minutes.
Turn cookie slices over and bake another 25 minutes.
Cool completely.
Notes
Store in an airtight container. For longer storage, store in the freezer. Nutritional values are approximate and based on 1/12 of the recipe.