Soak ground coffee in boiling water for 10 minutes, then strain using coffee filter or a very fine screen.
On medium to medium low heat 2 cups of milk, sugar and salt until steaming but boiling.
Mix 1/2 cup milk with corn starch, no lumps.
Pour milk & corn starch and coffee into into pan of hot milk. Stirring often. Keep on low heat and stir constantly until thicken. You want it thickened but you don't want to over cook it because the corn starch will break down and get runny.
Once thickened, stir in vanilla and remove from heat.
Pour into bowl and cool in refrigerator or freezer (cover with wrap to prevent skin forming on top).
When mixture is completely cold, pour into your ice cream machine and churn per machine instructions. Add optional cookies in the last 5 minutes of churn time. I have a cuisinart and it took about 25 minutes to make.
Put into freezer safe container with lid and store in freezer.