Preheat the oven to 180°C (356°F).
In a bowl, mix bread flour, baking powder, sugar, and salt.
Add cold butter and mix by hand until crumbly.
Add milk, egg, and cinnamon powder, and knead into a dough.
Flatten the dough and cut it into triangles.
Place on a baking sheet lined with parchment paper.
Bake at 180°C (356°F) for 18–20 minutes.