Preheat the oven to 350°F (175°C).

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.

Beat in the eggs one at a time, followed by the vanilla extract until well combined.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients into the wet mixture, stirring until just combined.

Gently fold in the rolled oats until evenly distributed.

Use a cookie scoop to drop rounded tablespoons of dough onto a lined baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 10-12 minutes or until the edges are lightly golden brown.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

In a bowl, whisk together powdered sugar and milk until smooth.

Drizzle the icing over the cooled cookies.