1. Prepare the Cinnamon Sugar Filling

In a small bowl, mix the brown sugar and cinnamon with a fork until evenly combined. Set aside.

2. Prepare the Cupcake Batter

1. Preheat the Oven: Set your oven to 350°F (177°C). Line a 12-cup muffin tin with cupcake liners. Line a second pan with 6-8 more liners since this recipe makes about 18-20 cupcakes.
2. Mix the Dry Ingredients: In a large bowl, sift together the flour, baking powder, baking soda, salt, and nutmeg. Whisk to combine and set aside.
3. Cream the Butter and Sugar: In a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the butter and granulated sugar on medium-high speed for 3-4 minutes, until light and fluffy.
4. Incorporate the Wet Ingredients: Scrape down the sides of the bowl. Reduce speed to medium-low and add the eggs, one at a time, mixing until just combined. Add the vegetable oil and vanilla extract.
5. Combine Wet and Dry Ingredients: Gradually add the dry ingredients in three additions, alternating with the buttermilk in two additions, beginning and ending with the dry ingredients. Mix until just combined.

3. Layer and Swirl the Cinnamon Sugar

1. Spoon 1 tablespoon of batter into each cupcake liner.
2. Sprinkle 1 teaspoon of cinnamon sugar filling on top.
3. Add another tablespoon of batter, followed by another teaspoon of cinnamon sugar.
4. Use a toothpick to gently swirl the layers together to create a cinnamon roll effect.

4. Bake the Cupcakes

1. Bake in the preheated oven for 16-18 minutes, or until a toothpick inserted in the center comes out clean.
2. Let the cupcakes cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

5. Prepare the Cream Cheese Frosting

1. In a stand mixer or large bowl, beat the butter and cream cheese until pale and fluffy (about 5-6 minutes).
2. Add powdered sugar, one cup at a time, mixing on low until fully combined.
3. Add vanilla extract and salt, then increase speed to medium-high. Beat for 5-7 minutes until light and fluffy.

6. Prepare the Cream Cheese Icing Glaze

1. In a medium bowl, beat the butter and cream cheese until smooth.
2. Add powdered sugar and mix on low speed.
3. Add vanilla and salt, then mix in milk 1 tablespoon at a time until you achieve the desired consistency.

7. Assemble the Cupcakes

1. Transfer the frosting to a piping bag fitted with a large round tip. Pipe a generous swirl onto each cupcake.
2. Place a mini cinnamon roll or mini cinnamon-flavored bread roll on top.
3. Drizzle the cream cheese glaze over the cupcake.
4. If using, sprinkle finely crumbled cooked chicken or beef for a unique contrast.