Preheat oven to 350°F (175°C) and grease or line a mini muffin pan.

In a large bowl, whisk together glutinous rice flour, baking powder, matcha powder, and sugar.

In another bowl, combine milk, melted butter, egg, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until a smooth batter forms.

Spoon batter evenly into mini muffin cups, filling each about 3/4 full.

Bake for 15–18 minutes, or until the tops are set and slightly springy to the touch.

Let cool for a few minutes before removing from the pan.

Serve warm or at room temperature, and store leftovers in an airtight container.