Preheat an oven to 180c (350f). Butter the bundt cake pan with room temperature butter and flour to prevent the cake from sticking to the pan.
In a large mixing bowl, add the flour, baking powder, and kosher salt, and mix with a whisk until combined. Set aside.
In a big mixing bowl, add the room temperature butter, sugar, vanilla extract, and lemon zest, and mix with an electric hand mixer until its creamy.
Add the greek yogurt (or sour cream), eggs, lemon juice, vegetable oil, and mix until the mixture is well combined.
Add the lemon extract, flour, and buttermilk. Mix until the mixture is almost combined. Finish mixing with a spatula until the mixture is just combined.
Pour the cake batter into the prepared bundt cake and spread it with an offset spatula. Bake in a 180c (350f) oven for about 40-50 minutes or until a toothpick inserted into the cake comes out clean.
Allow the cake to cool to room temperature before flipping the cake. Top the pan with a plate, flip the cake and tap the cake pan to release the cake from the pan.