Combine whole milk, heavy cream, lavender, and sugar in a 2 quart pot.
Heat over medium-low heat until a light simmer, but not boiling.
Remove from heat.
Let stand for 15 minutes.
Strain out lavender.
Stir in vanilla and salt.
Pour into ice cream machine.
Freeze according to packaging instructions.
Spoon out half the ice cream base into glass bowl.
Stir in food coloring.
Alternately spoon purple ice cream base with original into a freezer safe container.
Swirl together.
Freeze until hard.
Notes
Double check the lavender and make sure it's of the culinary variety. There are many different types and you don't want to buy one that's not meant for cooking! You should be able to find some at your local grocery store.
This recipe is gluten-free and vegetarian!
This recipe could also be served as a soft serve.
There are a few different ways to go about coloring this ice cream. If you just want the ice cream to purple, add your dye before freezing. If you want to marble it, add the dye to half the ice cream after it frozen. You could also not dye this recipe at all, if you don't want to!
Do not boil the milk mixture when you're cooking it.
Taste the ice cream base around 10 minutes of steeping. I don't recommend letting it sit longer than 15 minutes.