Preheat the oven to 350°F (175°C) and line a 12- or 18-cup muffin tin with cupcake liners.
In a large bowl, cream together the softened butter, 2 cups sugar, 1/2 tsp salt, and 2 tsp cinnamon until light and fluffy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla and sour cream until combined.
In a separate bowl, whisk together the flour and baking powder, then add the dry mixture to the wet ingredients and mix until just combined.
Fold in the Hershey's Cinnamon Chips until evenly distributed through the batter.
Spoon the batter into the prepared liners, filling each about two-thirds full.
Combine 3 tablespoons sugar and 1/2 tablespoon cinnamon in a small bowl, then sprinkle the mixture over each muffin evenly.
Bake for 17–18 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Remove the muffins from the oven and let cool in the pan for a few minutes before transferring to a wire rack to cool completely.