Preheat the oven to 350°F/176°C and line a muffin pan with cupcake liners.
If using fresh beets, peel and chop them into cubes. Then bring them to a boil over medium/high heat and cook until very soft and a fork easily pierces them, approx. 20-25 minutes. (You may also use canned beets for faster prep.) Once cooked, mash the beets to get 1 cup of puree. Make sure not to use more than 1 cup of beet puree.
Meanwhile, add the soy milk and apple cider vinegar to a small bowl and set it aside for 5 minutes to let it thicken and curdle. This is your vegan buttermilk.
Add the beet puree, your vegan buttermilk, vanilla, and maple syrup to a large mixing bowl. Stir until combined. If the beets weren't cooked enough and your batter looks lumpy, place all the liquids into your blender and process until smooth. Then return it to the bowl.
Now add all the dry ingredients to the same bowl and mix until combined, without overmixing.
Then divide the batter between your 12 cupcake tins and bake until a toothpick inserted in the middle comes out clean, approx. 18-20 minutes.
Let the muffins rest on a cooling rack until completely cooled before frosting them!
For the frosting
Add all the ingredients to your blender and process until completely smooth, starting with 5 tablespoons of maple syrup. Taste and add another tablespoon of syrup if you prefer it sweeter. Keep in mind not to go overboard, or the frosting will get too thin to pipe.
If the frosting gets warm as you're blending (this can happen in strong blenders), transfer it to a bowl and place it in the freezer for 30 minutes before piping your cupcakes.
Notes
Weigh your flour for the most accurate results. I highly recommend that you do not rely on cup measurements when baking. If you don’t have a kitchen scale, you may spoon the flour into your measuring cup and use a knife to scrape off the excess, with similar results. Do not scoop from the bag!If using canned beets, make sure they are not pickled! Use beets that are canned only in water, no vinegar or oil as that will alter the flavour.Use fresh and active baking powder. Baking powder that is open in your pantry for 6+ months can start to lose its effectiveness.If you do not have a powerful blender, soak your cashews in hot water for 30 minutes before blending your frosting. This will help them swell and soften, making them easier to blend into a smooth frosting.Make sure to press your tofu very well to remove excess liquid to prevent your frosting from getting too thin.If the frosting gets warm as you’re blending (this can happen in strong blenders), transfer it to a bowl and place it in the freezer for 30 minutes before piping the frosting onto your cupcakes.Let your cupcakes cool in the muffin pan for at least 10 minutes before handling them. Then transfer them to a cooling rack to completely cool BEFORE frosting them.These taste best on days 1-2, but you may store leftovers in the fridge for up to 4 days. Keep them in a sealed container to preserve moisture. Or freeze in a freezer-safe airtight container for up to 3 months.