In a large mixing bowl, melt the butter. Let the butter cool and whisk in the honey, egg yolks, vanilla, and espresso powder.
Whisk the dry ingredients into the wet ingredients: flour, cocoa, baking powder, salt, and cinnamon. If your flour is lumpy, try to whisk the lumps out before adding it to the wet ingredients.
Stir well to combine the ingredients, and let the batter rest while you prepare the skillet(s). Allow the batter to sit and rest for about 10 minutes--you’ll notice it thickens.
Butter a cast iron skillet (between 8-12 inches is ideal), or two small, individual-size cast iron skillets (pictured).
Fold the chocolate chips into the batter, and pour the batter into the prepared skillet.
Bake the brownie for about 22-25 minutes, in an 8-12 inch skillet. Or about 20-22 minutes for smaller cast iron skillets. Bake until the center looks set (it will still wiggle a bit). A toothpick inserted into the center should have "fudgy" crumbs on it. Allow the brownie to rest for about 5-10 minutes. Serve the brownie warm with homemade whipped cream or ice cream. Dive in with a spoon, and enjoy!
Notes
*If you don't want to use 12 tablespoons of butter, here's an alternative: 8 TB unsalted butter + ¼ cup coconut oil (both melted and cooled). **If you're using regular chocolate chips, add a bit more than 1/2 cup (a heaping 1/2 cup). Chocolate chips usually contain sugar, if not they'd be too bitter. Look for the best chocolate chips you can find. I like Enjoy Life and Equal Exchange brands. This brownie is meant to be enjoyed straight from the skillet. If you have leftovers, I recommend reheating pieces before serving them. This brownie is best when it's enjoyed warm.