Preheat the oven to 350°F and line a 12-cup standard muffin pan with cupcake papers.

In a large mixing bowl, whisk together buttermilk, oil, egg, and vanilla extract until thoroughly combined.

Sift flour, matcha powder, baking soda, and baking powder in another bowl, then add salt and sugar and whisk until evenly distributed. Combine the dry mixture with the wet ingredients to form a smooth batter.

Divide the batter evenly into 12 muffin cups and bake for 17 minutes, or until a toothpick inserted comes out clean with a few crumbs attached.

Allow the cupcakes to cool in the pan for 10-15 minutes, then remove and place them on a wire rack to cool completely.

To make the whipped cream, beat together heavy whipping cream, vanilla extract, and sugar until stiff peaks form.

Transfer the whipped cream to a piping bag fitted with your favorite tip, pipe a swirl on top of the cooled cupcakes, and dust with matcha powder. Keep refrigerated.