Preheat your oven to 200°F (95°C). In a large mixing bowl, combine all-purpose flour, instant dry yeast, optional poppy seeds, and fine salt. In a separate bowl, warm the buttermilk, granulated sugar, and unsalted butter until the butter is melted. Pour the warm mixture into the dry ingredients and stir until combined.

Add the large eggs one at a time to the mixture, stirring until fully combined after each addition. Gradually incorporate the fresh lemon zest. If the dough is too sticky, sprinkle a little more flour until it is tacky.

Cover the bowl with plastic wrap or a clean kitchen towel and allow the dough to rest for 10-20 minutes.

In a small bowl, combine brown sugar and more lemon zest. Massage the sugar and zest together, then whisk in the softened butter until it resembles a spreadable paste.

Turn the rested dough onto a floured surface and roll into a 12'x18' rectangle. Spread the lemon filling evenly over the dough and roll tightly. Slice into 12 equal pieces.

Place the sliced rolls in a greased baking pan. Cover with aluminum foil and turn off the oven. Let rise for 30 minutes in the warm oven.

Preheat the oven to 350°F (175°C). Bake for 28-32 minutes until golden brown and fluffy.

While baking, prepare the icing by whisking together powdered sugar, lemon juice, and melted butter until smooth.

Once cooled for 10-20 minutes, drizzle the icing over the rolls and garnish with additional lemon zest.