Break graham crackers into uneven crumbs, some fine crumbs, as well as big chunks of cookies.

In a small saucepan, melt the butter, sugar and cocoa powder over medium heat, stirring constantly.

Pour the melted butter mixture over the cookie crumbs.

Add cream cheese and mix until well combined.

Stir in chopped walnuts.

On the counter, line about 20-inch long  strip of plastic wrap.

Transfer the cookie mixture in the middle of the wrap and roll it into a 16-inch log, about 2 inches in diameter.

Tightly wrap the plastic wrap and freeze for at least 2 hours, or until firm.

Slice the log into half inch thick cookies before serving. Store in the freezer in an air-tight container.