Prepare the dough

Line a baking sheet with a silicone mat or parchment paper. Add 150 g flour to a bowl. Make a trough in center and add crumbled yeast and warm water and mix with until smooth. Let stand until mixture is foamy, 10 to 15 minutes.

Whisk 1 egg, melted butter, sugar, and salt thoroughly into yeast mixture. Add remaining flour. Fit a dough hook onto stand mixer and knead the dough on low speed until soft and sticky, 5 to 6 minutes. If dough is to sticky add some more flour. Transfer dough onto a floured work surface; dough will be sticky and elastic but not stick to your fingers. Form the dough lightly into a smooth, round shape, gently tucking loose ends underneath.

Wipe out stand mixer bowl, drizzle olive oil into the bowl, and turn dough over in the bowl several times to coat surface thinly with oil. Cover bowl with aluminum foil. Let dough rise in a warm place until doubled, about 1 1/2 hours. Transfer dough to a floured work surface and pat to flatten bubbles and form into a slightly rounded rectangle of dough. Dust dough lightly with flour if needed. Cut dough into 8 equal pieces. Form each piece into a round shape. Use your hands to gently pat and stretch the dough rounds into flat disc shapes. Arrange buns on baking sheet. Dust buns very lightly with flour. Cover with parchment paper and let buns rise for another 1 hour.

Baking the buns

Preheat oven to 190 degrees (Celsius) Beat 1 egg with milk in a small bowl, using a fork, until mixture is thoroughly combined. Very gently and lightly brush tops of buns with egg wash without deflating the risen dough. Sprinkle each bun with sesame seeds.

Bake in the preheated oven until lightly browned on top, 15 to 17 minutes. Buns will stick together slightly where they touch. Let cool completely, tear the buns apart, and slice in half crosswise to serve.