Combine the oats and soy milk in a jar or airtight container. Stir until evenly mixed.
Add the almond butter, chia seeds, matcha powder, and maple syrup. Stir well — the matcha will clump if you don't mix thoroughly. Make sure the green color is evenly distributed throughout.
Cover and refrigerate overnight or for at least 6 hours.
Before serving, top with sliced almonds and coconut flakes, and dust with a pinch of extra matcha. Eat cold or at room temperature.
Notes
Whisk the matcha into the soy milk first if you're getting clumps. A fork works better than a spoon.
Use culinary-grade matcha, not ceremonial. The flavor difference is undetectable in overnight oats.
Soy milk is the protein driver. Other plant milks drop the protein count.
Keeps refrigerated up to 3 days. Add toppings fresh each morning.