Preheat your oven to the temperature listed on the cake mix box (typically 325°F to 350°F).
Grease a 10-inch Bundt pan thoroughly.
Combine pecans, melted butter, brown sugar, and cinnamon (if using) in a bowl. Spread this mixture at the bottom of the pan.
Prepare the cake mix according to package instructions. Pour the batter over the pecan mixture in the pan.
Bake as per the cake mix instructions, but start checking a bit early. The cake is done when a tester comes out clean.
Cool the cake in the pan for 10 minutes. This patience is key to avoiding a crumbling cake during the grand flip.
Invert the pan onto a serving plate with a hopeful heart and a steady hand. Gently remove the pan to reveal your Upside Down Bundt Cake.
Let the cake cool completely before slicing. This wait time allows the caramelized pecan topping to achieve its sticky perfection.
Variations & Tips: