Preheat your oven to 350°F (175°C) to ensure even baking.
In a large mixing bowl, cream together 1 cup of room temperature butter, 1 cup of dark brown sugar, and ½ cup of sugar until light and fluffy, about 2-3 minutes.
Beat in 2 eggs, one at a time, then mix in 2 teaspoons of vanilla extract until well combined.
In a separate bowl, whisk together 2 ¾ cups of flour, 1 teaspoon of baking soda, and ½ teaspoon of salt. Gradually add this to the wet ingredients, mixing until just combined.
Gently fold in the frozen, sliced Milky Way candy bars until evenly distributed throughout the dough.
Drop heaping tablespoons of dough onto a baking sheet lined with parchment paper, leaving space between each cookie.
Bake for 10-12 minutes, or until the edges are golden brown and the centers are still soft.
Allow cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
