Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a large bowl, beat the softened butter and brown sugar together until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the vanilla and butterscotch extracts.
Gradually add the flour mixture to the butter mixture, alternating with the buttermilk and cream soda, beginning and ending with the flour mixture.
Mix until just combined.
Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.
Allow to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.
For the frosting, beat the softened butter until creamy.
Gradually add the powdered sugar, mixing on low speed until combined.
Add the heavy cream, vanilla extract, butterscotch extract, and a pinch of salt.
Beat on high for 2-3 minutes until fluffy.
Once the cupcakes are completely cool, frost them generously with the butterscotch buttercream.