Preheat your oven to 350 degrees. Line two muffin tins with paper liners and set aside.

Combine 2/3 cup butterscotch chips in a microwave safe bowl with the water. Heat until melted making sure to stir every 20 seconds. Set aside.

Stir together the flour, baking soda, baking powder, and salt in a large measuring bowl. Set aside.

Whisk together the butter and both sugars in the bowl of an electric mixer until fluffy. Add the eggs, one at a time, followed by the vanilla extract. Slowly stir in the slightly cooled melted butterscotch mixture. Fold in the dry ingredients with the 1 cup of milk until incorporated.

Divide between your prepared pan and bake 15-17 minutes or until a toothpick comes out clean. Cool completely.

Place the 1 cup of butterscotch chips in a glass bowl. In a saucepan heat 1/2 cup heavy cream until just simmering. Pour over your chips and allow to sit for 5 minutes. Whisk until smooth. Fill each cupcake with 1 tablespoon of the mixture making sure to reserve 3 tablespoons for the frosting.

Place a clean mixing bowl in the freezer for 15 minutes. Once chilled whisk 2 cups heavy cream with 3 tablespoons of your butterscotch filling until fluffy. Pipe onto your cupcakes and enjoy.