Preheat the oven to 425ºF. Place muffin liners in muffin tin.
In a small bowl, combine the flour, sugar, baking soda, baking powder, and salt. Set aside
In a larger bowl, combine the egg, milk, sour cream, vegetable oil and vanilla extract. Whisk to combine.
Sift in 1/4 of the flour mixture at a time, gently folding the batter, until all of the flour is incorporated.
Add in the cherries and chocolate chips, fold again to combine.
Fill each muffin cup full with batter. I like to use a cookie scoop to scoop batter into each cup, the batter will be thick. This gives each muffin a nice dome top. Sprinkle sanding sugar on top of each muffin.
Place the muffin pan in the middle of the oven and bake for 5 minutes at 425ºF. Then keeping the pan in the oven, reduce the oven temperature to 400ºF and continue to bake for 15-17 minutes or until a toothpick inserted in the center comes out clean.
Allow the muffins to cool for about 3 minutes in the pan, then take the muffins out and allow them to cool upside down on a cooling rack. This will help create muffins with a dome top.