Preheat the oven to 350 °F (175 °C). Butter and flour two 8‑inch cake pans (lining bottoms with parchment rounds helps ensure release)

In a large bowl, cream together 9 Tbsp butter, granulated sugar, and lemon zest until light and fluffy. Beat in egg yolks one at a time, then stir in vanilla extract

In a separate bowl, whisk dry ingredients: flour, baking powder, baking soda, and salt

Gently fold the dry mixture into the butter mixture, alternating with Greek yogurt, until just combined

Beat egg whites until soft peaks form, then fold them into the batter gently to preserve airiness

Coat one-third of the raspberries with a tablespoon of flour and gently fold into batter to prevent sinking

Divide batter evenly between pans, top with remaining raspberries and extra lemon zest for garnish

Bake for about 30 minutes (up to 50 minutes in conventional ovens) until a toothpick inserted in center comes out clean; let cool 10 minutes in pans before turning out onto wire racks

For the frosting: beat butter until smooth, then gradually add confectioners’ sugar and lemon juice until fluffy and spreadable. Adjust sweetness or tartness as needed; tint with food coloring if desired

Once cake layers are fully cool, frost between layers, then top and sides. Chill before slicing if preferred