Prep: Line a baking sheet with parchment paper and set aside.
Flour mixture: In a small mixing bowl, stir together flour, matcha powder, and salt. Set aside.
Butter mixture: In a large mixing bowl, use an electric hand mixer to beat the butter until very creamy and slightly pale in colour. Add the powdered sugar and vanilla extract and beat until well combined.
Combine: Add the flour mixture and mix until just combined. Add the heavy cream and mix until combined. The dough will be thick but pipeable. Transfer the dough to a piping bag fitted with a large piping tip.
Pipe dough: Pipe the dough onto your lined baking sheet in a ring shape by squeezing the bag firmly. If you don't like how one turns out, you can scrape it up and add it back to the piping bag. The dough will become easier to pipe as it warms up in your hands. Leave about 1-2" in between each cookie for spreading.
Chill & preheat oven: Chill the entire baking sheet in the fridge for 30 minutes to let the dough firm up which will help the cookies keep their shape better. Preheat the oven to 325°F while you wait.
Bake: Bake cookies for 15-17 minutes. Bake for longer for more crisp cookies. Let the cookies cool completely before decorating.
White chocolate: Melt the white chocolate in the microwave in 10 second intervals or on the stovetop at very low heat. Dip each cookie into the melted white chocolate, let the excess drip off, and place it on parchment paper to firm up.
Decorate: Arrange sprinkles on top of the white chocolate before it fully sets. I used some holly sprinkles to create a wreath look but you can do anything you want! Let the white chocolate fully set before serving or packing away.