Pre-heat the oven to 350℉ and line a 8x8 pan with parchment paper
Melt the butter & sugar, take off heat right before butter is all the way melted.
in a large bowl whisk together the melted butter & sugar combo, whisk in the powder sugar until well combined. This should take about a minute and it will be thick.
next add eggs, and vanilla and combine for about another minute.
next add lemon juice and lemon zest and whisk until well combined.
Add the fresh milled flour and stir to combine and let sit for about 5 minutes
Add the batter into prepared pan and smooth it out
bake until 18-25 minutes (this will vary when using fresh milled, depending on how fine your flour is, start with 18 minutes and keep a close eye. The edges will be barley browned & a toothpick will come out pretty clean with a few crumbs. Should be pretty light in color. Cool on a wire rack.