Combine coffee grounds and milk in a glass container and give it a stir.

The next day, use a French press to extract the coffee milk. (Discard the spent coffee grounds).

Measure out the coffee milk and top off with extra milk to a total of 125 ml (the coffee grounds may have absorbed some milk).

Whisk together 3 egg yolks along with sugar and vanilla extract in a heat-safe bowl.

Heat up the coffee milk in a small saucepan until scalding hot and add in the lavender.

Remove from heat and let it steep for 5-10 minutes.

Strain out the lavender using a sieve (save it for later) and return the infused coffee milk to the saucepan over medium heat.

While whisking the egg yolks, gradually stream in the hot coffee milk slowly (tempering the egg yolks) until all of the coffee milk is incorporated with the eggs.

Transfer the mixture back into the saucepan and whisk over medium heat until thickened.

It's ready once the mixture can coat the back of a spoon/spatula and you can draw a line through it.

Pour the custard mixture through a sieve into the cold heavy cream and give it a stir.

Add the lavender back into the ice cream base (optional), cover and chill in the fridge for at least 6-8 hours.

Pour the chilled ice cream base into your ice cream maker and churn according to the manufacturer's instructions.