Combine the non-dairy milk, sugar, and agar in a medium saucepan. Bring just barely to a simmer over medium-high heat stirring constantly to dissolve the sugar and agar. Simmer for 3 minutes on low, stirring constantly.
Pour the mixture into a high-speed blender, add the matcha powder, and blend for 30 seconds.
Divide the mixture among 8 6-ounce ramekins or cups. Refrigerate for at least 2 hours.
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Notes
If you don't completely dissolve the agar powder and sugar, the mixture will stay separated and only some of your panna cotta will set. Make sure to stir constantly.Non-dairy milk can be prone to separation and curdling. It is important not to bring the milk to a boil, and instead bring it to a very light simmer. The proteins in most non-dairy milk react this way and you need to keep your eye on it if it's on heat.I prefer the creamy texture that full-fat coconut milk brings to this recipe. Oat milk, almond milk, soy milk, and other non-dairy milk work, but don't provide as much creaminess. You get more of a jello-y consistency. Non-dairy milk that has a high flavor profile like pistachio or hazelnut milk will affect the taste of the recipe.