Preheat oven to 350°F. Butter three 8-inch round cake pans and line with parchment paper. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter. Add sugar and mix until incorporated. Add sifted matcha powder and mix until combined. Scrape down bowl as needed to ensure thorough mixing.
Add honey. Add eggs one a time, mixing on low speed until incorporated.
In a large bowl, whisk together flour, salt, and baking powder. Add flour mixture in three additions, alternating with buttermilk. Start and end with flour mixture. Mix until just combined. Be careful not to overmix.
Divide cake batter among the prepared cake pans. Level batter, if necessary. Bake for 30-35 minutes until toothpick inserted in center of cake comes out clean. Allow cake to cool in pan for 3-5 minutes before unmolding. Allow cakes to cool to room temperature on wire racks.