The same recipe can yield very different results if the chocolate is used as a chip or melted. As a chip it is a particle carried by the batter, melted it contributes to the fat to flour ratio.
Here is the recipe I like.
3,600g cocoa pwd
10,000g pastry flour
10,800g chocolate chip
Yield 12 sheets.
For what I called fudge brownies 25% of the butter would be melted with the chocolate and added to the creamed sugar/butter. Proceed as normal, then bake until edges just begin to raise. Almost an egg-set firmness.
For cake brownies- cream sugar/butter add egg, etc. add chips & bake until set.