Combine the sugar, cocoa powder, salt, undissolved yeast and 1 1/2 cups of the flour in a large bowl. Melt the butter in a small saucepan over low heat. Add the milk and vanilla and heat until warm (120 to 130 degrees F).
Add the butter mixture to the dry ingredients. With an electric mixer, mix on medium speed, gradually adding the egg and remaining cup of flour, until smooth and sticky, about 2 minutes. Fold in the chocolate chips and cherries.
Let the batter rest for 10 minutes. Generously grease a 12-cup muffin pan. Portion the batter into the pan and let it rise until doubled, about 1 hour.
Preheat the oven to 375 degrees F. Bake the muffins until a toothpick inserted in the center of one comes out clean, 20 to 25 minutes.