Start by warming the milk until it’s just lukewarm, then mix in yeast and let it sit for about 10 minutes. Add flour, butter, egg yolk, sugar, and salt into the mixture. Knead the dough until it becomes smooth and elastic, which usually takes around 7–10 minutes.
Place the dough in a bowl and cover it with a towel or plastic wrap. Allow it to rise in a warm place for 1.5 to 2 hours until it becomes puffy and doubles in size. This step is key for achieving a soft and airy texture.
Blend basil, parsley, pine nuts, parmesan, olive oil, and salt until combined. The texture should be slightly coarse, not overly smooth, to give better flavor pockets. Taste and adjust seasoning if needed.
Roll the dough into a large rectangle and spread pesto evenly across it. Roll it tightly into a log, then cut it lengthwise to reveal the layers. Twist the two halves together carefully, keeping the filling visible on top.
Transfer the twisted dough into a lined loaf pan or baking tray. Brush with butter and sprinkle sesame seeds on top. Bake at 175°C for 50–60 minutes until golden brown and fully cooked inside.