Heat a couple of tablespoons of oat milk in the microwave. Do not heat it for too long; you don't want the oat milk too hot or the matcha will become bitter.
Add matcha green tea powder. Whisk until dissolved.
Combine the matcha mixture with oat milk.
Add lavender simple syrup. Stir to combine.
Pour into a glass with ice.
Notes
To make a hot lavender match latte, bring oat milk to a low simmer in a small pot over medium heat. Don't let the oat milk get too hot. You want the temperature to be 176° F (80° C) or cooler so the matcha doesn't become bitter.Remove the saucepan from the heat, then pour the matcha tea powder and lavender simple syrup into the saucepan and whisk.You can froth the matcha mixture as well. If you don't have a handheld frother, you can shake the mixture in a mason jar.