Preheat the oven to 325°F. Grease and line an 8"x8" (or 9"x9") square baking pan with parchment paper.
Begin by placing the chocolate chips and dairy-free butter in a microwave safe bowl. Microwave in 30 second intervals until completely smooth and melted, stirring well with a rubber spatula in between. This usually takes me a total of 1 minute 30 seconds. Set aside to cool for a few minutes.
Place the brown sugar and all 3 eggs in the bowl of a stand mixer (or a large bowl with a hand mixer). Use the whisk attachment to beat on medium-high for 4-5 minutes until light and bubbly. Stop and scrape down the sides of the bowl occasionally with a rubber spatula.
Pour the melted chocolate mixture into the sugar and egg bowl. Whisk on medium speed for 1-2 minutes to fully incorporate the chocolate. Stop and use a rubber spatula to scrape the bottom and sides.
Add the flour, cocoa powder, and salt to the bowl. Fold with the rubber spatula until you have a homogenous batter. Pour the brownie batter into the square pan, smoothing the top with the spatula and tapping the pan against the counter to remove any air bubbles.
Bake for 35-37 minutes (8"x8" pan). If using a 9"x9" pan, begin to check the brownies around 30 minutes. Insert a toothpick into the centre of the brownie pan to check for doneness. There should be a few moist crumbs attached when removed. If you see gooey wet batter, leave them in the oven and check again in 2-3 minutes.
Once done, remove the pan from the oven and allow brownies to cool completely in the pan. They will be too difficult to remove from the pan when hot. After about 2 hours, remove brownies from the pan by gently lifting the parchment paper. To achieve clean brownie cuts, run a large metal knife under hot water for 1 minute. Dry the knife and make a slice. Repeat, cleaning and heating the knife after each cut, until you have 16 perfect brownies. Enjoy!