Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper or silicone baking mats
Beat the softened butter, brown sugar, and granulated sugar in a large bowl until light and creamy
Add the eggs one at a time, mixing well after each addition. Mix in the vanilla extract.
In a separate bowl, whisk together the flour, baking soda, and fine salt.
Gradually add the dry ingredients to the butter mixture. Mix just until combined.
Fold in the rolled oats and butterscotch chips until evenly distributed throughout the dough.
Melt the caramel candies with the milk in a small saucepan over low heat, stirring until smooth. Remove from the heat and stir in the salt.
Scoop the cookie dough onto the prepared baking sheets, leaving about 2 inches between portions.
Add a small amount of salted caramel to each cookie and gently swirl it into the surface.
Bake for 10 to 12 minutes, until the edges are lightly golden and the centers still look slightly soft.
Remove from the oven and immediately sprinkle the warm cookies lightly with flaky sea salt.
Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack.
