Preheat your oven to a low setting of 200°F (95°C).

In a stand mixer bowl, combine all-purpose flour, instant dry yeast, poppy seeds, and fine salt. Whisk buttermilk, granulated sugar, and unsalted butter together, microwave until warm, then mix into dry ingredients.

Add large eggs one at a time to the dough, ensuring each is integrated before the next. Gradually sprinkle in more flour until the dough is tacky but not sticky.

Cover your bowl with a clean kitchen towel and let the dough rest for about 10 to 20 minutes.

Prepare the filling by mixing granulated sugar, light brown sugar, and fresh lemon zest. Incorporate softened unsalted butter until creamy.

Flour your work surface, roll the dough into a rectangle, spread lemon filling, roll tightly, and cut into 1-inch sections using dental floss.

Place cut rolls into a greased 9x13 pan, cover with foil, and let them rise in a warm oven for about 30 minutes.

Preheat your oven to 350°F (175°C) and bake the rolls for 28 to 32 minutes, until golden brown.

While cooling, mix icing ingredients until smooth and creamy.

Cool the rolls for 10 to 20 minutes, then drizzle icing over and garnish with fresh lemon zest.