Take half a block of Medium Firm refrigerated tofu (this is not the silken tofu product that comes in unrefrigerated boxes such as Mori-Nu brand or other brands) or what would be roughly equivalent to 1 cup of chopped tofu.
Sandwich the tofu block with two pieces of paper towel and between two heavy plates. Let the water drain out of the tofu to soak the paper towels. After 10 minutes, remove and replace the paper towels with dry ones.
Repeat this process again after 10 minutes with dry paper towels, then check the tofu. If the paper towels are quite wet, replace with dry paper towels and let the tofu be pressed for an additional 10 minutes.
Once the tofu block is pressed relatively dry, remove the tofu from under the heavy plates and cut the tofu into cubes to fill a ‘1 cup’ measuring cup. Set aside.
Halfway through the tofu draining process, you can start to prepare the soy milk mixture. Mix the cornstarch and soy milk until well blended in a small pot.
Heat this soy-cornstarch mixture on a low stove heat setting, stirring frequently with a wooden spoon. After 5-10 minutes of this, the mixture will begin to thicken. Once it thickens to a watery glue-like consistency, quickly turn off the heat, and move the pot to a separate cool burner. (This mixture will continue to thicken over time, so it is best to use it to make the frosting as soon as you can.)
Immediately measure out ¼ cup (or 4 tablespoons) of this soy-cornstarch mixture into a small bowl and stir in 2 tablespoons of maple syrup. Mix until thoroughly incorporated.
Put this soy/cornstarch/maple syrup concoction with the cup of chopped tofu into a food processor and pulse for 1-2 minutes, stopping often to scrape down the sides of the container using a rubber spatula.
Once fully blended and mixed together, the frosting should be a smooth creamy texture. Check the consistency to see if you need to add a little bit more plant-based milk (add 1-2 teaspoons at a time as needed) or a little bit more sweetness.
While the tofu is draining, you could be doing other things in the kitchen, like finishing up the cake you are baking! If you like, you can also press out the tofu earlier in the day or the day before. Just keep the pressed tofu in the fridge to stay refrigerated until you use it to make the frosting.
This cake frosting will have an off-white creamy tinge due to the brown maple syrup. It will also look the same if honey, brown sugar or agave nectar is used. So if you are looking for a completely white cake frosting, you may need to use powdered sugar or white sugar in place of the maple syrup. Since the powdered sugar or white sugar is not liquid, you can adjust the recipe by adding a teaspoon or two more of the plant-based milk when blending if needed.
Keep the frosted cake, muffins or cupcakes refrigerated until serving time. Store leftover frosting or frosted baked goods in the refrigerator.