Preheat the oven at 350° F.
Grease an 8x½-inch or 9-inch loaf pan with butter, and then add a teaspoon of flour. Rotate and tap the pan until flour covers the greased surface and discard the excess flour.
Alternatively, grease the pan with non-stick oil spray.
Melt the butter on low-medium heat in a small saucepan. Or microwave for 30-40 seconds on high. Set aside.
Sift together flour, baking powder, baking soda, and salt. Whisk well for at least 30 seconds.
Add sugar and stir well to combine.
In a mixing bowl or measuring cup, add yogurt, milk, vanilla, and orange zest.
Mix everything well until the mixture is smooth.
Add melted butter to the yogurt mixture and mix well.
In the dry ingredients, add the wet mixture in three batches, mix until well combined.
Do not overmix.
Transfer the batter into a prepared loaf pan and smooth the top with a spatula or spoon.
Bake this cake for 40-50 minutes or until the inserted cake tester or toothpick in the center comes out clean.
Because every oven is different, keep an eye on the cake after 40 minutes of baking time.
If the top of your cake is browning too quickly, cover it loosely with aluminum foil.
Remove the pan from the oven and transfer it onto a cooling rack.
Allow the cake to cool down in the pan for about 20-25 minutes. Then remove the cake from the pan and place it on the cooling rack.
Let the pound cake cool completely before slicing.