Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, whisk together melted butter, brown sugar, eggs, and vanilla extract until smooth.
Add in the flour, salt, and baking powder, mix until smooth. Fold in the crushed Oreo cookies. Evenly divide the batter between the paper liners. Bake for 12-15 minutes.