Biscoff Oatmeal Cookie Pies with Whipped Coconut Filling

In a medium pot or saucepan, bring milk, flour, and sugar to a boil. Boil for 5 minutes without stirring, then turn off heat and add vanilla. Cool mixture completely, to room temperature. You can place the pot (on a potholder) in the freezer to speed up this process–just make sure it does not overcool.
In the meantime, whip butter with an electric mixture until light and fluffy, about 5 minutes. Add cream of coconut and beat for another minute. Add cooled milk mixture and beat for another 5 minutes, until completely smooth.
Fold in sweetened coconut flakes and refrigerate until ready to frost cookies.