Pre-heat oven to 350 F. Grease a square baking pan, or round 8’inch baking pan with non-stick spray or butter.
Whisk together the dry ingredients, flour, baking powder, baking soda, and salt in a bowl and whisk it and set it aside.
Using a handheld mixer or kitchen aid, beat butter and sugar on high speed until light and creamy, about 2-3 minutes. Add eggs one at a time, followed by lemon zest and lemon juice, vanilla. Beat for another 1 minutes and it is mixed in and it looks fluffy. Scrape the bowl in between while mixing.
Add half of the flour mixture, followed by buttermilk and mix on low speed and add rest of flour and buttermilk mixture. Mix until just combined. Do not overmix.
Pour cake batter into the prepared pan and bake until its golden in color and center is baked when you test it with a toothpick for 30 minutes.