Preheat oven to 350°. Line 24 muffin cups with paper liners.
In a large bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. In another bowl, whisk flour, baking powder and salt; add to creamed mixture alternately with milk, beating well after each addition. Fold in crushed cookies.
Fill prepared cups three-fourths full. Bake 20-22 minutes or until a toothpick inserted in center comes out clean. Cool in pans 10 minutes before removing to wire racks to cool completely.
In a large bowl, combine butter, confectioners’ sugar, milk and vanilla; beat until smooth. Fold in cookie crumbs. Pipe or spread frosting over cupcakes. If desired, sprinkle with additional cookie crumbs and garnish with mini Oreo cookies.