Blanch the spinach in boiling water for 30 seconds, then squeeze out the water completely. Blend 100g of blanched spinach with 60g of water until smooth.

Mix bread flour, salt, sugar, instant dry yeast, and egg in a bowl. Add the blended spinach mixture and knead until the dough forms a cohesive ball. Add butter and continue kneading until the dough is smooth.

Let the dough rise for 50 minutes or until it doubles in size.

Punch down the dough to release air, divide it into 40g portions, and shape each into a round ball. Let them rest for 15 minutes for intermediate proofing.

Flatten each ball into a tadpole shape using your palm. Roll out the top part with a rolling pin, then hold the bottom part and roll it into a triangular shape. Roll tightly from the top to form a spiral roll.