Preheat your oven to 350°F (175°C). Prepare your Bundt pan.

In a large mixing bowl, combine cake mix, eggs, vegetable oil, buttermilk, and vanilla extract. Beat on medium speed for 2 minutes.

In a separate bowl, whisk together brown sugar, flour, and cinnamon. Slowly stir in melted butter until crumbly.

Spray Bundt pan with nonstick spray. Pour half of the cake batter into the pan, then sprinkle half of the cinnamon swirl mixture. Swirl to combine.

Add the remaining cake batter and top with the rest of the cinnamon swirl mixture. Swirl gently.

Bake for 40-45 minutes or until a toothpick comes out with a few crumbs. The top should be golden.

Allow the cake to cool in the pan for 15 minutes before inverting onto a wire rack.

Blend cream cheese, melted butter, vanilla extract, and powdered sugar until smooth for the glaze.

Drizzle the glaze over the cooled cake and sprinkle with sanding sugar.