Activate the yeast
In a small bowl, mix warm milk, yeast, and 1 tsp sugar. Let sit for 5–10 minutes, until frothy.

Make the dough
In a large bowl (or stand mixer with a dough hook), combine flour, sugar, cardamom, salt, and orange zest.
Add yeast mixture and eggs. Mix until combined.

Add butter
Gradually add softened butter, one cube at a time, kneading until each piece is absorbed.
Continue kneading for about 10–12 minutes (stand mixer) or 15 minutes by hand, until the dough is smooth and elastic.
It should be soft but not sticky.

First rise
Transfer dough to a lightly greased bowl, cover with plastic wrap, and let rise in a warm place for 1½–2 hours, until doubled.

Shape the loaf
Punch down the dough. Roll out into a rectangle (~10×14 inches).
Brush with melted butter, sprinkle with brown sugar, cardamom, and orange zest (if using).
Roll up tightly from the short side and place seam-side down in a greased 9×5-inch loaf pan.
Alternatively, you can braid or twist the dough for a marbled effect.

Second rise
Cover loosely and let rise again for about 45–60 minutes, until puffy and nearly doubled.

Bake
Preheat oven to 350°F (175°C).
Bake for 30–35 minutes, until golden brown and internal temperature reads about 190°F (88°C).
Tent with foil if browning too quickly.

Glaze (optional)
Mix powdered sugar with orange juice to form a thin glaze.
Drizzle over warm loaf and let cool slightly before slicing.