In a small saucepan or microwave-safe bowl, combine the 80g milk and 56g butter. Heat until the butter is melted. Stir in the 60g water and 5g vanilla. Ensure the temperature is between 105°F–115°F before proceeding.
In your stand mixer bowl, whisk together 260g of the flour, the 50g sugar, 7g yeast, and 3g salt. Pour in the warm milk mixture and the 100g eggs. Mix until a slurry forms, then gradually add the remaining 165g flour. Knead for 5–7 minutes until the dough is smooth and tacky but clears the sides of the bowl.
Place the dough in a greased bowl. Cover and let it rise in a warm, draft-free spot until doubled in size (60–90 minutes).
In a small bowl, combine the 100g sugar and 12g lemon zest. Rub them together with your fingers to release the oils. Stir in the 18g poppy seeds.
Punch down the dough and roll it into a large rectangle.Brush the surface with the 56g softened butter.Sprinkle the lemon-poppy sugar evenly over the butter.Cut the dough into 6 long strips, stack them, and then cut that stack into 4 rectangles. Arrange the squares vertically in a greased 9x5 inch ceramic loaf pan. Cover and let rise for 45 minutes. Preheat your oven to 350°F. Bake for 30–35 minutes until the internal temperature reaches 190°F and the top is deep golden.
Whisk the 120g powdered sugar, 30g lemon juice, and 15g cream. Drizzle over the bread while warm.
