Preheat oven to 350 degrees. Use butter or cooking spray to grease your bundt pan really well, making sure to get in all the crevices. Then, flour the pan. Set aside.
In a mixing bowl, whisk together the flour, baking powder, salt, and poppyseeds. Set aside.
Zest your lemons (I leave my zest in large pieces, I use the cheese grater to do this). Add the zest to a mixing bowl with the sugar. Whisk until well combined.
Add the softened butter and mix until everything is creamed together - and is light and fluffy.
Add the vanilla and eggs and mix.
Add the milk and lemon juice and mix until combined.
Slowly add the flour mixture into the wet mixture, mixing between each addition.
Bake for about 55 minutes, or until the top is golden brown and a toothpick inserted comes out clean. Let cool for10 minutes and then run a knife around the edge of your pan before turning the lemon poppyseed bundt cake out onto a cooling rack. Let cool for 15-20 more minutes before pouring the glaze on.
While the cake is cooling, make the glaze. Whisk together all the glaze ingredients and adjust amounts until you have your desired taste and texture. Pour over the cake and sprinkle some extra lemon zest on top if you would like.
