Preheat the oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.

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

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In another bowl, whisk together the flour, baking soda, and salt. Gradually add to the butter mixture, mixing until just combined.

Fold in the chocolate chips or M&Ms.

Spread the cookie dough evenly in the prepared baking pan.

Bake for 20-25 minutes or until the edges are golden and a toothpick inserted in the center comes out clean.

Allow the cookie cake to cool completely in the pan.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing well. Add milk and vanilla extract until the frosting reaches the desired consistency.

Divide the frosting into three bowls. Leave one bowl white, and color one bowl red and the other blue using food coloring.

Once the cookie cake is completely cool, frost the top with the white frosting.

Using a piping bag, decorate with red and blue frosting to create festive designs.