Preheat the oven to 325°F and spray a 12-cup Bundt pan very well with nonstick cooking spray, making sure to coat every curve and crease.

In a large bowl, combine the dry yellow cake mix, dry instant pudding mix, and eggs, then beat with an electric mixer on medium speed until smooth and combined; the batter will be thick at first.

Pour in the vegetable oil and mix until incorporated, then add the 7.5 ounces of 7-Up and mix on low speed just until smooth.

Pour the batter into the prepared Bundt pan and spread it evenly with a spatula if needed.

Bake for 45 to 50 minutes, until the top is lightly browned and a cake tester or toothpick inserted into the thickest part of the cake comes out clean, checking around 45 minutes.

Let the cake cool in the pan for about 20 minutes, then carefully turn it out onto a wire rack or serving plate and let it cool completely, about another 40 minutes, before glazing.

Whisk the powdered sugar and 1/4 cup 7-Up together in a small bowl until smooth, adding more powdered sugar if too thin or a tiny splash more soda if too thick to drizzle.

Drizzle the glaze over the completely cooled cake, add sprinkles if desired, then slice and serve at room temperature.