It's super simple, but I wanted to share.
1) Prepare chocolate chip cookie dough. I used a vegan cookie dough mix from the local grocery store; it's actually marketed for gluten allergies, but I simply removed the egg replacer from the instructions and prepared as normal (up until the baking step). I'm sure you could just add a mix like that in with some extra milk, but this is how I did it (because I had cookie dough left over from another project).
2) Put the first 5 ingredients into a blender, and blend until smooth and creamy.
3) Add ice cream and blend until you have the perfect vegan milkshake!
Source of recipe: This is just the basic concept of a formula I stumbled across whilst preparing a proper Sunday Dessert. I'm using a dollop as a "measurement" here, just do what makes you feel good. No one knows what sweet craving you have but you!