Preheat your oven to 375°F (190°C) and prepare an 8-inch square baking pan with parchment paper or non-stick spray.

Cream softened butter and granulated sugar in an electric mixer until light and fluffy, about 2 minutes.

Incorporate eggs one at a time and add vanilla extract, mixing until fully combined.

In a separate bowl, whisk together all-purpose flour, salt, and baking soda, then gradually add to wet ingredients.

Fold in peppermint chips carefully with a spatula to distribute evenly.

Spread the dough evenly in the prepared baking pan and bake for 25 to 28 minutes.

Allow the bars to cool in the pan for 10 minutes then transfer to a wire rack to cool completely.

Prepare the frosting by creaming softened butter, then gradually mix in powdered sugar and milk to achieve spreadable consistency.

Once cooled, frost the bars generously and sprinkle additional peppermint chips on top for decoration.