Preheat the oven to 350°F and lightly grease a 13x9-inch baking pan. In a stand mixer, blend the softened butter and cream cheese until smooth. Pause to scrape down the bowl, then add the sugar and continue mixing until the mixture becomes light and airy. Incorporate the eggs and extra yolk, followed by the vanilla extract, mixing well. In a separate bowl, whisk together the flour, salt, and baking powder. Gradually integrate the dry ingredients into the cream cheese blend, pausing to scrape down the sides to ensure an even mix. Fold in ¾ cup of mini chocolate chips along with 18 crushed Oreos. Spread the batter evenly into the prepared pan. Scatter the remaining 2 tablespoons of mini chocolate chips and the 6 crushed Oreo pieces on top. Bake for 30 to 35 minutes, or until the edges just begin to turn a golden hue. Let cool thoroughly before slicing into bars.