Preheat your oven to 350F.  Lightly grease a 9x9 pan and cut a piece of parchment to fit exactly on the bottom of the pan.  This will help unmolding the cake much easier later.

Add the tempered butter into a mixing bowl with a paddle attachment.  Mix until the butter is smooth. Add the granulated sugar and cream together with the butter until combined.  Add the lemon zest and the eggs one at a time. Scrape the bowl in between each addition.

Combine the salt, flours, and baking powder.  Add the flours in two to three additions. Mix until combined.  Pour the batter into the prepared pan and bake for 40-45 minutes or until golden brown and baked through.