Add matcha powder to a small bowl with 2 tablespoons of warm water. Whisk until smooth with no dry clumps. Add the matcha paste to the milk and whisk again until fully combined.
In a jar or container with a lid, combine rolled oats, chia seeds, Greek yogurt, maple syrup, vanilla extract, and pinch of salt. Pour in the matcha milk and stir well until everything is evenly mixed. Stir again 5 minutes later to redistribute the chia seeds before they set.
Seal the jar and refrigerate for at least 6 hours — overnight is best. The oats will absorb the liquid and thicken significantly.
Open and stir. If the oats are thicker than you’d like, add a splash of milk and stir until you reach the right consistency. Taste and add more honey if needed.
Add toppings just before eating — fresh fruit, granola, a drizzle of honey, toasted pistachios, and a dusting of matcha powder. Eat straight from the jar or transfer to a bowl.