Soak the cashews: Place the cashews in a medium bowl, cover with water, and let them soak for at least 8 hours. This softens them for blending. Optionally, add 1 teaspoon (5.7 g) of salt to the water to help activate the cashews and neutralize enzyme inhibitors. After soaking, drain and rinse the cashews.
Blend the cashews and maple syrup: In a high-speed blender or food processor, blend the soaked cashews and maple syrup until smooth, forming a thick, sticky paste. If you lack these appliances, substitute cashew butter for whole cashews.
Mix in the brownie ingredients: If using a blender, transfer the cashew mixture to a medium bowl and fold in the almond flour and cocoa powder using a spatula. If using a food processor, add the almond flour and cocoa powder to the cashew mixture and process until well combined. The mixture should be thick and dough-like.
Press into a pan: Transfer the brownie mixture to a parchment paper-lined baking dish (5.5 x 7.5 inches/14 x 19 cm) and press into a smooth, even layer.
Prepare the chocolate topping: In a medium bowl, whisk together the melted coconut oil, cocoa powder, and maple syrup until smooth.
Assemble the brownies: Pour the chocolate mixture over the brownies and spread evenly. Tap the dish to release any air bubbles.
Chill: Refrigerate the brownies for about 1 hour until firm. Once firm, lift the brownies out using the parchment paper and cut them into squares. For clean cuts, run a sharp knife under hot water, wipe it dry, and cut slowly, reheating the knife as needed.
Store: Keep leftover brownies in an airtight container in the refrigerator for up to 2 weeks, or freeze for up to 3 months. When freezing, transfer the brownies to the refrigerator 24 hours before serving to avoid condensation on the chocolate.