1. Prepare the Oven and Muffin Tin: Getting Ready to Bake

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Line Muffin Tin: Line a 12-cup muffin tin with paper or silicone cupcake liners.
   • Tip: You can also grease the muffin tin if you don’t have liners.

2. Combine Dry Ingredients: Ensuring Even Distribution

1. Whisk Together: In a large bowl, whisk together the flour, granulated sugar, baking powder, salt, and cinnamon until well combined.

3. Combine Wet Ingredients: Creating a Flavorful Base

1. Melt Butter: In a small saucepan or microwave-safe bowl, melt the ½ cup of unsalted butter.
2. Whisk Together: In a separate large bowl, whisk together the melted butter, milk, eggs, and vanilla extract until well combined.

4. Combine Wet and Dry Ingredients: Forming the Batter

1. Gradually Add Wet to Dry: Gradually add the wet ingredients to the dry ingredients, mixing on low speed with an electric mixer or stirring with a rubber spatula until just combined. Be careful not to overmix.
2. Fold in Sour Cream: Add the sour cream to the batter and gently fold it in using a spatula until the batter is smooth.

5. Prepare the Cinnamon Sugar Mixture: A Sweet and Spicy Swirl

1. Combine Brown Sugar and Cinnamon: In a small bowl, mix together the ¼ cup of brown sugar and 1 tablespoon of ground cinnamon until well combined.

6. Assemble the Muffins: Building Layers of Flavor

1. Fill Liners: Fill each muffin liner about halfway with the batter.
2. Sprinkle with Cinnamon Sugar: Sprinkle a generous amount of the cinnamon-sugar mixture over the batter in each liner. The original recipe does not specifically call for a cream cheese layer, but rather mixes the sour cream directly into the batter. For a cream cheese swirl, you could mix 8 oz softened cream cheese with 1/4 cup of sugar and layer it in between the batter, as well as swirl it on top.
3. Top with Batter: Top with the remaining batter, dividing it evenly among the liners. Each liner should be about ¾ full.
4. Add More Topping: Sprinkle the remaining cinnamon sugar mixture over the top of the batter in each liner.

7. Bake to Perfection: Achieving Golden-Brown and Tender Muffins

1. Bake: Bake in the preheated oven for 18-20 minutes.
2. Check for Doneness: The muffins are done when a toothpick inserted into the center comes out clean, or with just a few moist crumbs attached. The tops should be golden brown.

8. Cool and Glaze (Optional): Adding a Sweet Finish

1. Cool in Tin: Let the muffins cool in the muffin tin for about 10 minutes before transferring them to a wire rack. This allows them to firm up slightly.
2. Prepare Glaze (Optional): If desired, make a simple glaze by whisking together 1 cup of powdered sugar and 2 tablespoons of milk until smooth. Add the vanilla extract.
3. Drizzle: Drizzle the glaze over the cooled muffins.
4. Cool Completely: Let the muffins cool completely on the wire rack before serving.