Preheat the oven to 400°F (200°C) and position the rack in the center. Using a fork, pierce the sweet potato several times. Place a sheet of aluminum foil on the oven rack to catch any drips, then place the sweet potato directly on top of the foil. Bake for approximately 1 hour and 15 minutes, or until the potato is completely tender when pierced. Remove from the oven and allow it to cool on a wire rack for 10 minutes.

While the sweet potato is baking, line a standard 12-cup muffin tin with paper liners or lightly grease the cups with cooking spray. Set aside.

In a medium mixing bowl, whisk together the flour, baking soda, cinnamon, baking powder, salt, nutmeg, and chopped pecans. Set this dry mixture aside.

Once the sweet potato is cool enough to handle, peel it and measure 1 cup of the flesh. Transfer it to a large mixing bowl. Whisk in the egg and melted butter until the mixture is smooth. Then incorporate the maple syrup, whole milk, and lemon juice, stirring until fully combined.

Gently add the dry ingredients to the sweet potato mixture. Stir with a wooden spoon or silicone spatula until the dry ingredients are just moistened. Avoid over-mixing to ensure tender muffins.

Spoon the batter evenly into the prepared muffin cups, filling each approximately three-quarters full. Bake in the preheated oven for 18 to 20 minutes, or until a toothpick inserted into the center of a muffin emerges clean.

Transfer the muffin tin to a wire rack and allow the muffins to cool in the pan for 10 minutes. Then remove the muffins from the tin and let them cool directly on the wire rack for an additional 5 minutes.

While the muffins are cooling, prepare the glaze by whisking together the sifted confectioners’ sugar, cinnamon, and milk in a small bowl until smooth and pourable.

Once the muffins are slightly cooled but still warm, drizzle the glaze over the tops using a spoon or fork. Allow the glaze to set for several minutes before serving.