Step 1: Prepare the Muffin Batter

1. Preheat oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
2. In a bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon.
3. In another large bowl, beat butter, granulated sugar, and brown sugar until fluffy.
4. Add eggs one at a time, then mix in vanilla extract.
5. Gradually add dry ingredients to the wet ingredients, alternating with buttermilk. Mix until combined.

Step 2: Make the Cream Cheese Filling

1. In a small bowl, beat cream cheese, powdered sugar, vanilla extract, and cinnamon until smooth.

Step 3: Assemble the Muffins

1. Fill each muffin cup halfway with the batter.
2. Spoon about 1 teaspoon of cream cheese filling into the center.
3. Cover with more muffin batter, filling cups about 3/4 full.

Step 4: Bake the Muffins

1. Bake for 18-22 minutes until golden brown. A toothpick inserted into the muffin (not the filling) should come out clean.
2. Let muffins cool in the pan for 5 minutes before transferring to a cooling rack.

Step 5: Prepare the Cinnamon Glaze

1. In a bowl, whisk powdered sugar, milk, cinnamon, and vanilla extract until smooth.
2. Drizzle the glaze over slightly warm muffins.