Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper to prevent sticking and ensure easy cleanup.
In a large mixing bowl, pour in the melted butter, granulated sugar, and brown sugar. Use a whisk or an electric mixer to blend the ingredients together until the mixture becomes smooth and creamy.
Add the eggs and vanilla extract to the sugar-butter mixture. Beat well until everything is completely combined, creating a rich and fluffy batter.
In a separate bowl, whisk together the flour, cocoa powder, salt, and baking powder until well mixed to avoid clumps.
Carefully fold the dry ingredients into the wet mixture using a spatula or wooden spoon. Mix until just combined, taking care not to overmix to preserve the cookies' tenderness. If using, gently fold in the semi-sweet chocolate chips for an extra layer of chocolaty goodness.
Scoop approximately 1 tablespoon of brownie batter and shape it into a disc in your palm. Place an Oreo cookie in the center of the disc, then wrap the brownie batter around the cookie to create a sealed ball. Repeat this process with the remaining batter and Oreos until complete.
Arrange the cookie balls on the prepared baking sheet, leaving adequate space between them to allow for spreading during baking.
Place the baking sheet in the preheated oven and bake for 10-12 minutes. Keep an eye on them; the cookies are ready when the edges feel set and the tops display slight cracks. Avoid overbaking for the perfect chewy texture!
Once baked, let the cookies cool on the baking sheet for about 5 minutes. Then, transfer them to a wire rack to cool completely, allowing the flavors to meld.
Notes
Serve warm with cold milk for the best experience.