Add baking powder, baking soda, and cardamom to the yogurt or sour cream in a small bowl.
Mix it together and let it sit for about 10 minutes.
In a large bowl, whisk eggs and sugar together.
Add flour to the eggs and sugar, and mix together.
Add a pinch of salt.
Add melted butter, and mix together.
Gently stir in your sour cream/yogurt into the large bowl.
Heat up your waffle iron and grease it with butter.
Add a ladle full of batter to the waffle iron, and cook until the waffle is golden brown. The waffle should be soft.
Serve your waffles hot, room temperature, or cold. These are sweet on their own and can be eaten plain, but you may serve with maple syrup if desired.