Preheat the oven to 350 degrees Fahrenheit and lightly grease an 8x8 dish, or 8- to 9-inch round pan.
In a mixing bowl, stir together the sprinkles and cake mix. Add the oil and aquafaba and stir to combine it as well as you can (it will be lumpy and dry, and that's fine).
Add the nondairy milk and stir to mix it in well. Make sure to keep stirring to break up lumps; the batter should come together into a thick, frosting-like texture. Only if absolutely necessary, add more milk 1 tablespoon at a time to bring the batter together.
Use a spatula (you'll need it - this batter is thick) to transfer the batter into the greased pan and spread it out evenly all the way to the edges.
Bake for 22 to 25 minutes, or until the edges are just starting to turn brown.
Let cool for AT LEAST thirty minutes before slicing in order to achieve the best texture.
Leftovers will store in an airtight container for a few days.