Mix pudding and milk together with a wire whisk. Whisk until smooth and all powder is dissolved. Refrigerate for 5 minutes to thicken.

Place 10 whole Oreo cookies into a quart size plastic bag and crush with a rolling pin.

Trim the edges of the round cake to fit into the trifle dish. Discard edges. Slice the cake in half and place one half into the bottom of the trifle bowl. Add half of the pudding on top of the cake. Add half of the whipped topping and spread evenly. Sprinkle with half of the crushed cookies. Repeat the layers in the dish.

After the final layer of whipped topping, add 5 whole Oreo cookies to the top and add remaining crushed cookies.

Cover and refrigerate until ready to serve.