Creating Cinnamon Roll Muffins is a straightforward process. Follow these simple steps for delicious, mouthwatering results:

1. Preheat the Oven: Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners or coat with non-stick spray.
2. Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, granulated sugar, and ground cinnamon until well combined.
3. Combine Wet Ingredients: In another bowl, beat the egg and then add the buttermilk, melted butter, and vanilla extract. Mix until fully combined.
4. Combine Mixtures: Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix!
5. Make the Cinnamon Filling: In a small bowl, mix the brown sugar, ground cinnamon, and softened butter until you get a crumbly mixture.
6. Fill Muffin Tin: Spoon a small amount of muffin batter into each muffin cup, followed by a generous sprinkle of the cinnamon filling. Top with more batter until each cup is about ¾ full.
7. Swirl: Use a toothpick to gently swirl the cinnamon filling into the batter, creating a marbled effect.
8. Bake: Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
9. Cool: Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.
10. Prepare the Glaze (Optional): In a small bowl, whisk together powdered sugar, milk, and vanilla extract until smooth. Drizzle over cooled muffins for an extra sweet touch.

These steps guide you in creating incredible Cinnamon Roll Muffins that are sure to impress!