Preheat oven to 400°F.

Fill a medium-sized pot with two inches of water and place a steamer basket on top, so that the water sits just below it. Then place the sweet potatoes in a single layer on top. Bring the water to a gentle simmer and cover the pot with a lid. Steam until the sweet potatoes are soft enough to pierce (and mash) with a fork, about 10 to 12 minutes.

Transfer the sweet potatoes from the steamer to a bowl or sheet pan and allow them to cool, about 5 to 8 minutes.

Remove the skins and then, in the bowl, mash with a fork until smooth and “chunk” free. Set aside.

Line a mini muffin pan with paper liners. In a medium bowl, mix the dry ingredients (flour, baking powder, and cinnamon) together. Then, add the egg, milk, sugar, applesauce, 1 cup of mashed sweet potatoes, banana, and vanilla. Mix again until everything is combined and the batter is smooth.

Fill each muffin tin 3/4 of the way full with batter. Shake the pan a little to settle the batter. Then place the muffin pan into the oven and bake for 12 to 15 minutes, or until a knife inserted into the middle comes out clean. When done, let the muffin pan rest on the counter to cool.

Meanwhile, in a medium bowl, mix the second cup of mashed purple sweet potatoes with 1/2 cup of yogurt. (Note: you may have some leftover sweet potato, so simply save it for lunch or dinner or use as a sandwich spread). Stir until smooth and the “frosting” takes on a uniform purple hue -- although a swirly, marbled look is nice, too! But be careful to not overmix -- you want the frosting to remain a bit thick. Then, use a spoon or spatula to transfer the frosting into a plastic bag or a piping bag, if you own them. If using a plastic bag, push as much of the frosting towards one of the lower corners and twist at the top, removing as much air as possible from the bag. Then snip off the end. When muffins are cool, frost the tops.