Preheat the oven to 325°F. Thoroughly spray an 8" or 9" square pan with pan spray. Cut a square of parchment to fit in the bottom of the pan, and then spray again.
Over medium-low heat, melt the 2 sticks of butter and the milk powder over medium-low heat. Set aside.
Whisk together the cocoa powder and flour, and set aside.
In your stand mixer bowl or in a metal bowl, whisk the four eggs, espresso powder, granulated sugar, brown sugar, salt, honey, and vanilla over a double boiler of simmering water until the sugar is mostly dissolved and the mixture is about 125°F.
Place the bowl on the mixer (or use a hand mixer) and whip on high speed until lightened and fluffy and at the ribbon stage, about 7-8 minutes.
Once the egg/sugar mixture is nice and light, drizzle in the butter/milk powder mixture on medium speed. Mixture should still retain its nice texture, so add the butter slowly (over about 1 minute) so the emulsion doesn't break.
Stop the mixer, add the cocoa powder/flour mixture, and whisk on medium-low speed until most of the dry ingredients are incorporated, about 30 seconds.
Finish mixing by hand with a spatula, scraping down to the bottom of the bowl to make certain everything is evenly mixed.
Scrape batter into your prepared pan. Smooth the top and bake on the center rack until set, shiny, and beautiful, about 35-40 minutes in a 9" pan and a few extra minutes in an 8" pan.
Let cool on a rack for a few minutes, then lift out using the parchment and allow them to cool completely before slicing and enjoying.
Notes
Nutritional information is based on cutting the brownies into 20 bars.You can use American (non-alkalized) cocoa powder if you would like. Since there is no leavener other than air bubbles, the pH isn't a serious issue.If you would like the "OG" version of this recipe because you have enjoyed it in the past, I encourage you to try this version. It is better! Die hard fan of the original? Just email me and I'll be happy to send you that version.