Take cornflour and milk in a sauce pan. Add sugar and mix well.
Heat and cook till it comes to a simmer. Cook till it thickens.
Now add in one mashed banana and vanilla. Mix well. Set aside.
Take a serving cup. Crumble some cookies in the base. Spoon the banana filling and top with more crushed cookies. Top with banana and cream.
Crumble more cookies on top.
Chill for few hours.