Preheat oven to 350 degrees F (176 C) and lightly grease a standard 9-inch round cake pan or 8x8-inch baking dish and dust with gluten-free flour. Shake out excess and set aside. (I also think you could use an 9-inch cast iron skillet, but it wouldn't come out as easily and will likely have to be served directly from the pan).

In a liquid measuring cup, measure out non-dairy milk and add vinegar or lemon juice. Set aside.

Add chickpea brine to a medium mixing bowl and begin whipping until loose peaks form. Then add sugar in a little at a time and beat until the texture is glossy and white and semi-firm peaks form.

Add dry ingredients to a large mixing bowl and whisk to combine. Then add almond milk mixture and oil and whisk once more. Lastly, add the whipped chickpea brine (with sugar) and gently whisk/fold in until a thick but pourable batter is formed.

Add batter to prepared cake pan and bake on a center rack for 25-35 minutes, or until the edges are light golden brown and a toothpick inserted into the center comes out completely clean.

Let cool completely in the pan - set on a wire rack to speed cooling process. To remove, run a dull knife around the edge of the cake pan to loosen, then slice and serve. Alternatively, place a plate on top and quickly invert. It will be upside down so flip onto another serving platter to get it right side up.

Serve with vegan butter and maple syrup. Pairs extremely well with hearty dishes like Vegan Lentil Chili.

Store covered at room temperature for 2-3 days, or in the refrigerator for 3-4 days. Freeze up to 1 month.