Preheat oven to 180ºC (356ºC). Grease and flour a large bundt pan (see notes) or grease and flour a 9” large springform cake pan if not using a bundt. Set aside.
Melt butter first and then set aside to cool slightly.
In a large mixing bowl, or the bowl of an electric stand mixer (if using), combine flour, baking powder, sugar, poppy seeds and lemon zest, mix well.
Add eggs, milk, lemon juice, vanilla and the cooled melted butter.
Beat for 30 seconds on high speed until well combined, scraping down the sides as needed.
Pour into cake pan and smooth out the top with a spatula.
Bake 35-40 minutes or until a skewer inserted into the middle comes out clean. The cake should be set and spring back when gently pressed.
Remove and cool in pan for 10 minutes.
Remove cake from pan and transfer to a wire rack to cool completely.