Preheat your oven to 350°F (175°C) and line your muffin tin with cupcake liners.

In a large mixing bowl, whisk together the dry ingredients: flour, baking powder, baking soda, ground cinnamon, and salt.

In a separate bowl, beat together the softened butter and granulated sugar until light and fluffy, about 3-4 minutes.

Add the large eggs one at a time, and then mix in the vanilla extract until well incorporated.

Gradually add the dry mixture to the butter and sugar mixture, alternating with the sour cream, and mix until just combined.

Combine brown sugar and cinnamon in a small bowl, add melted butter, and stir until it forms a paste.

Spoon batter into each muffin cup, add a layer of cinnamon paste, and top with more batter, swirling gently with a toothpick.

Bake for 18-22 minutes, or until a toothpick inserted comes out clean. Cool in the tin for 5 minutes before transferring to a wire rack.

Whisk together powdered sugar, milk, and vanilla extract to prepare the glaze, achieving a smooth consistency.

Drizzle glaze over cooled cupcakes and serve with a warm beverage.