Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Cream together the softened butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.

Incorporate the egg and vanilla extract, beating until fully combined and smooth, about 1 minute.

Whisk together the all-purpose flour, baking powder, and salt in a separate bowl, then gradually add to wet ingredients and mix on low speed until just incorporated.

Portion the dough into 7-8 large balls on the prepared baking sheet, leaving space for spreading. Flatten each ball to about 3/4 inch thickness.

Bake for 12-13 minutes until edges are lightly golden, then let cool for 10 minutes.

Prepare the butterscotch frosting by beating softened butter until smooth, then gradually add powdered sugar, butterscotch syrup, and heavy cream.

Once cookies are cool, pipe or spread the frosting on each cookie and add sprinkles immediately.

Enjoy fresh or store in an airtight container for up to 3 days. Freeze unbaked dough for up to 2 months.