Gently mix and set aside for 5 minutes for the yeast to bloom.
Once the yeast has bloomed, add in the flour, espresso powder, cocoa and fit your mixer with a dough hook.
Mix on low just until loosely combined.
Add in the butter while the mixer is running stopping if need be to scrape down the sides.
After 3 minutes of mixing, add in the salt. You never want to add the salt directly to the yeast as that will kill it on contact.
Mix until a soft, smooth elastic ball forms; ~8-10 minutes. The dough should pull away from the sides of the bowl but still be wet/tacky to the touch. If need be add a tablespoon of flour or so to help combine. If it’s too dry, add a tablespoon of water.
Remove the dough from the bowl and place on a very lightly floured surface.
Give it a few kneads to form the dough into a smooth ball tucking the ‘ends’ underneath.
Place in a lightly oiled bowl (at least 2-3 times bigger than the ball) and cover with plastic wrap. If you have a bread proofer, just place in an oiled bowl and into the proofer at 78F. Both should be in a draft-free place. Alternately you can place this whole bowl in the refrigerator (covered) overnight. The slow cold rise will help build the flavors.
Allow to rise until doubled in size; about 60-90 minutes.
When ready to use, preheat oven to 425F with the rack in the middle.
Lightly spray a 9×13” metal pan and then line with parchment (leaving a 1” overhang).