Whisk milk and pudding mix until dissolved in a bowl.
Add cream and cake extract, mix well.
Pour into Ninja Creami pint without overfilling.
Freeze flat for 24 hours with lid closed.
Remove, then place in Ninja Creami outer bowl.
Lock and press Ice Cream button to start.
Check texture; if crumbly, use Re-spin function.
Create a 1.5-inch well in ice cream.
Cut cake into small pieces and add.
Close lid, press Mix-in to blend.
Scoop into dishes; add optional garnishes.