In a gallon-size Ziploc bag, crush the oatmeal cookies. Add the melted butter to the bag and squish together until well combined.
Immediately press the cookie mixture into the bottom of a lined 9 or 10-inch springform pan, using your hands or the back of a spoon. Place the cookie crust in the refrigerator for an hour.
While the crust is chilling, shave the chocolate. If your kitchen is warm, you should place the chocolate shavings into the refrigerator until ready to use.
In a medium bowl, whip the heavy cream until soft peaks form.
In a large bowl, beat the cream cheese until smooth and creamy. Beat in the confectioner's sugar and Baileys Irish Cream. Gently fold in the whipped cream until well combined. Stir in 3/4 of the chocolate shavings. Spread the filling evenly over the cookie crust. Refrigerate overnight.
Just before serving, remove cheesecake from the springform pan and sprinkle with the remaining chocolate shavings.