Preheat the oven to 375 degrees and grease a standard muffin pan generously with non-stick cooking spray then set aside
Add the butter and granulated sugar to a large mixing bowl and cream together for about 2 minutes until the mix is smooth and well combined. Then add egg, vanilla, milk and sour cream and mix until even.
To the butter mix, add flour, baking powder, baking soda, cinnamon and salt. Use a rubber spatula to fold in until it just combines. Ensure not to overmix
Transfer batter with a spoon into the greased muffin pan, filling each tin to about ⅔ its volume. Insert a toothpick in the center of each batter-filled tin
Transfer the muffin pan to the preheated oven and bake for about 25 minutes or until the inserted toothpick comes out clean.
After baking, allow the muffins to cool in the muffin tin for 1-2 minutes, then move to a wire cooling rack.
For The Topping:
Melt the butter for the topping in a small container. Meanwhile, mix the granulated sugar and cinnamon together in a different container.
Once the muffins are out of the oven and have cooled for just a few minutes, use a pastry brush to brush a thin layer of melted butter over each muffin.
Generously sprinkle cinnamon-sugar mixture over the butter layer. Serve warm and enjoy
Tips
The baking powder starts to work as soon as the wet and dry ingredients are blended, so it’s important to have the oven preheated and pans ready before you combine the two.
If you have any leftovers, you can store them till ready to consume. Allow cooling completely, then freeze in a zip-log bag for up to a month. When ready to use, thaw at room temperature or in the refrigerator or microwave for a few seconds, until warm.