Preheat oven to 350 degrees and prepare a loaf pan by spraying with non-stick cooking spray.
In a large bowl, combine flour, baking powder, salt, and sugar.
In a small bowl, combine egg, milk, vanilla extract, and yogurt or sour cream.
Add the dry ingredients to the wet and stir to combine. You can use a large wooden spoon for this, if you wish.
In a small bowl, combine swirl ingredients together - ⅓c. sugar, 2 t. cinnamon, and 2 T. water. Use a tablespoon to drop spoonfuls of this mixture over the bread, then use a knife to swirl designs to incorporate the cinnamon mixture into the bread.
Bake for 45 - 50 minutes or until you insert a toothpick and it comes out clean.
Remove the bread from the oven and transfer it to a cooling rack to cool for 15 minutes.
Meanwhile, make the glaze ingredients by combining ½ c. powdered sugar with 1 tablespoon of milk.
When the bread has cooled completely, pour the glaze over the top and serve.
Recipe by The Gingham Apron at https://www.theginghamapron.com/cinnamon-swirl-bread-2/