Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the vanilla cake mix, eggs, vegetable oil, buttermilk, and 1 teaspoon of vanilla extract. Stir until smooth.

In a separate bowl, mix the brown sugar, all-purpose flour, and cinnamon for the cinnamon swirl. Drizzle the melted butter into the dry mixture and combine.

Pour half of the cake batter into a greased bundt pan. Sprinkle half of the cinnamon mixture over the batter, then add the remaining batter and top with the rest of the cinnamon mixture.

Use a knife to gently swirl everything together.

Place the bundt pan in the preheated oven and bake for about 45 to 50 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out clean.

While the cake cools, mix the softened cream cheese, softened butter, 1 teaspoon vanilla extract, and powdered sugar with a splash of milk until smooth.

Once the cake has cooled completely, invert it onto a platter and drizzle the cream cheese glaze over the top.

Sprinkle with granulated sugar and cinnamon.