Crush the Oreos in a food processor until finely ground. Pour into a mixing bowl with the butter and use a fork to combine. Press mixture into the bottom and up the sides of a 9-inch pie pan. Refrigerate crust while you work on the truffle layer.

In a food processor, pulse 10 ounces of the animal cookies until broken into fine crumbs. Add 5 ounces of the cream cheese and continue pulsing until well blended. Spread truffle mixture evenly into the crust. Return to the refrigerator.

In the well-chilled bowl of a stand mixer fitted with a whisk attachment, beat the heavy cream until soft peaks form. Add powdered sugar and vanilla, and continue whipping until stiff peaks form. Transfer whipped cream to another bowl and place in refrigerator to keep chilled.

Return bowl to mixer. Switch whisk attachment out and replace with paddle attachment. Beat the remaining 3 ounces of cream cheese and pudding mix together until combined. Gradually add the milk, a little at a time, allowing mixture to come together after each addition.

Remove bowl from the mixer and fold in about 3/4 of the whipped cream until just combined. Pour filling over the truffle layer and smooth out the top.

Transfer the reserved whipped cream to a pastry bag or small ziploc bag with the tip cut off, and decorate the pie as desired. Garnish with the remaining animal cookies and sprinkles*. Refrigerate for at least 4 hours before serving.