Start by preheating your oven to 350°F (175°C). Next, line two baking sheets with parchment paper to prevent sticking.
In a large mixing bowl, combine the softened butter, granulated sugar, and brown sugar. Beat them together with an electric mixer on medium speed until the mixture is light and fluffy, which should take about 3-4 minutes.
Add the eggs to the butter-sugar mixture one at a time, beating well after each addition. Then pour in the vanilla extract and mix until just incorporated.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing on low speed until fully combined; be careful not to overmix. The dough should be thick and slightly sticky.
Using a tablespoon or a cookie scoop, drop rounded portions of dough onto the prepared baking sheets, making sure to space them about 2 inches apart. Slightly flatten each mound of dough with the palm of your hand.
Bake the cookies in the preheated oven for about 10-12 minutes. They are done when the edges turn a light golden color. Once baked, remove them from the oven and let them cool on the baking sheets for about 2-3 minutes. Then, transfer the cookies to wire racks to cool completely.
After the cookies have cooled, generously spread a thick layer of chocolate frosting on the top of each cookie to create a base for the hat.
Place an Oreo cookie on top of the frosting, positioning it so it resembles the brim of a pilgrim hat.
For the finishing touch, secure a small edible candy to the top of the Oreo, symbolizing the buckle of the hat. You can use a bit of extra frosting to help it stick if necessary.
Allow the frosting to set for a few minutes before serving to ensure it holds its shape.
Notes
For an inviting Thanksgiving presentation, arrange the cookies on a decorative platter with autumn-themed decorations.