On the stove top in a small saucepan over medium low heat, melt the butter or coconut oil with the chocolate chip. Remove from heat and set aside to cool slightly.
In the bowl of the mixer, beat the eggs and sugar (s) until pale yellow. With the mixer on low, continue with the remaining master mix ingredients, mixing thoroughly.
Take half of the batter and mix into the melted chocolate mix, by hand. Set aside
In the remaining master mix batter, add the remaining pumpkin brownie ingredients, scraping the edges if necessary to make sure all is incorporated.
In your greased pan, scatter globs of the chocolate brownie mix, using most of the batter, but leave parts of the pan that are not covered with it.
Now grab the pumpkin brownie mix, and scoop all the batter into the empty spaces (and then some, most chocolate will be covered). Add the remaining chocolate anywhere you see fit!
Using a butter knife, gently swirly the mixture in snaking "s" motion throughout to marble the batters. Do not overdo it and start mixing it all together. When you achieve a marbled look you want, place in a preheated oven and bake for 35-45 minutes until the center is just set. Same concept modeled here in a video.
Let cool completely before cutting.
Recipe via tessadomesticdiva.com