Heat the oven to 350℉. Prepare a 9x13 baking pan by spraying with nonstick cooking spray, or line the pan with parchment paper for easy removal.
In a small mixing bowl, whisk together the flour, baking soda, and salt.
2 cups all-purpose flour, ½ teaspoon baking soda, ½ teaspoon sea salt
In a larger bowl, or the bowl of a stand mixer, add the melted butter and light brown sugar. Use an electric mixer and beat for 2 minutes on medium-high speed. The mixture should be pale in color and fluffy looking.
1 cup (2 sticks) salted butter, 1 ½ cups packed light brown sugar
Add in the eggs and vanilla extract, and beat just until combined.
2 large eggs, 1 tablespoon vanilla extract
Add the bowl of dry ingredients into the wet mixture, and beat on low speed just until no flour streaks remain in the dough.
Stir in the chopped Oreo cookies and chopped Cookies n' Cream chocolate bars until combined. * You can either reserve some for top of the blondies, OR use additional chopped Oreos and chocolate on top. 1 cup chopped Oreo cookies, 1 cup chopped Hershey Cookies n' Cream candy bars
Evenly spread the dough into the prepared baking pan. If wanted, add some additional chopped Oreo cookies and/or cookies & cream bars on top. *It's easiest if you drop large spoonfuls of it all over, rather than dump it in one pile, and then spread it out. Bake for 22-26 minutes. The edges should be lightly golden brown and look 'wrinkly' and the middle should still look somewhat pale and puffy.
Remove the bars from the oven and allow them to cool completely in the pan before cutting and serving. They can also be eaten warm, but they will continue to set while cooling, which will make them easier to cut.