Start by preheating your oven to 180°C (350°F).
Grease your cake pan with butter and dust it lightly with flour.
Combine milk and butter in a small saucepan and let the butter melt over low heat.
Remove the saucepan from the heat, then add saffron and mix --- set aside.
Sift and combine flour and baking powder in a medium-sized bowl.
In a separate (larger) bowl, combine eggs and sugar.
Use a hand mixer and mix until you it gets pale in color.
Add the flour and baking powder.
Pour the cooled butter, milk, and saffron.
Mix the batter --- just enough to combine everything.
Pour the saffron cake batter into the prepared cake pan.
Tap the pan on the countertop to get rid of bubbles.
Place the cake pan in the lower part of the oven for about 35 to 40 minutes, or when a toothpick comes out clean when inserted.
Set aside to cool, then dust with powdered sugar.
Slice your Swedish saffron cake and serve. Dust with more powdered sugar, if desired.