Preheat the oven to 350ºF and line a 8-inch square baking dish with parchment paper. In a large food processor fitted with an S-blade, process the rolled oats briefly, until they resemble a coarse flour.
Add in the black beans, almond butter, cacao powder, ground flax, vanilla, sugar, vinegar (which helps the brownies rise), salt, and baking soda. Process until a very smooth and thick batter is formed, stopping to scrape down the sides at least once to make sure everything is mixed evenly. Add 1/2 cup of the chocolate chips to the batter, and pulse briefly to mix them in.
Transfer the batter into the lined 8-inch baking dish. The batter will be rather thick, so you'll need to use the spatula to spread it evenly into the pan. Sprinkle the remaining chocolate chips over the top, and press them lightly into the batter.
Bake until the top begins to crack and the center feels relatively firm to a light touch, about 30 minutes. Allow the brownies to cool completely before attempting to cut them into squares, as they are fragile when warm. I let mine cool for at least 2 hours. Serve at room temperature, and store any leftovers in an airtight container in the fridge for up to a week. (I imagine these would freeze well, too!)
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Notes
Nutrition information is for 1 of 16 brownies. This is automatically calculated, and is just an estimate, not a guarantee.
If you prefer a darker chocolate brownie, go ahead and use 1/2 cup of raw cacao powder in this recipe. I've tested it that way, and I thought they were delicious, but they were a little "too dark" for some of my taste testers.
I imagine that any other nut or seed butter, such as peanut butter or sunflower seed butter, would work well in this recipe if you'd prefer to replace the almond butter.
You can use any vinegar that you have on hand. I've tested these with balsamic and apple cider vinegar.
Coconut sugar gives these brownies much of their substance and texture, so don't be tempted to use a liquid sweetener or sugar substitute without expecting significantly different results. Granulated sugar = chewy, fudgy brownies, so keep that in mind.
You can leave out the rolled oats for a grain-free dessert. They are just slightly more gooey and fragile that way.