Preheat the oven to 350 degrees Fahrenheit.
Rinse and drain 1 1/2 cups canned lentils, then add them to a blender.
Add 2 tablespoons cold water, 1 teaspoon vanilla extract, 1/2 cup maple syrup, and 1/3 cup cocoa powder to the blender, then blend until smooth.
Transfer that mixture to a mixing bowl.
Add 1/2 cup creamy almond butter, then mix well.
Add 3/4 cup whole wheat flour, then mix until incorporated.
Add 1/2 cup chopped dark chocolate, then mix until incorporated.
Transfer the brownie batter to an 8-inch square baking dish lined with parchment paper, then spread in an even layer.
Bake for 25 minutes, then let the brownies cool off for at least 20 minutes before serving.