Warm the milk in a saucepan over a low heat.
Mix the flour, sugar, egg yolks and vanilla seeds in a separate saucepan until smooth, then whisk in the warm milk, a little at a time, until smooth. Place the pan onto the heat and cook over a gentle heat for 2-3 minutes, stirring continuously.
Whisk in the Kahlúa and continue to whisk until the mixture thickens, about 15-25 minutes.
Remove the pan from the heat and stir in the chocolate and butter until melted and smooth.
To serve, spoon the mixture into serving glasses. If eating warm, sprinkle with lightly crushed [Chocolate Chip Oatmeal Cookies | https://www.halfbakedharvest.com/moms-simple-oatmeal-chocolate-chip-cookies-best-oatmeal-chocolate-chip-cookies-around/].
To chill the pudding, cover the serving glasses and place in the fridge, serve as directed above with warm cookies.