Place beaters and mixing bowl in freezer for later use.

Melt milk chocolate chips in a double boiler or microwave at 50% power for about 2 minutes.

Allow the melted chocolate to cool.

In a separate bowl, whisk together sweetened condensed milk and milk until smooth.

Whisk the cooled melted chocolate into the condensed milk mixture.

Stir in vanilla extract, ground cinnamon, and cayenne pepper.

Remove the chilled bowl and beaters from the freezer.

Beat heavy cream until stiff peaks form.

Gently fold the whipped cream into the chocolate mixture.

Transfer 3 cups of the mixture to a freezer-proof bowl and cover it.

Pour the remaining chocolate mixture into the Oreo cookie pie crust.

Freeze both the bowl and the pie for at least 2 hours.

After 2 hours, top the pie with the mixture from the freezer-proof bowl.

Freeze the pie overnight.

Before serving, garnish the pie with whipped cream and chocolate shavings, if desired.