Crush 2 Oreo with a rolling pin and add them to a plate. Spread some chocolate sauce or melted chocolate across the edges of the serving glass. Gently roll the edges of the glass over the Oreo crumbs.
To a blender jar, pour milk & add ice cream, vanilla (or chocolate sauce). Crumble half the amount of cookies and add them. Blend or pulse until smooth, taking care not to overblend.
Crush the rest of the cookies and add to the shake. Pour to serving glass and garnish with whipped cream & crushed Oreos.
Slice the banana and freeze overnight. Add it to a blender with chilled milk, vanilla and chocolate sauce. Blend until smooth & frothy.
Crush the oreo cookies and pulse just until combined & frothy. Pour to serving glass & garnish with crushed Oreos.