Preheat your oven to 325°F (165°C) and grease a bundt pan.

2. In a large mixing bowl, combine the cake mix, pudding mix, eggs, 1/2 cup water, vegetable oil, and 1/2 cup rum. Mix until smooth.

3. Stir in the chopped nuts, if using, until evenly distributed in the batter.

4. Pour the batter into the prepared bundt pan and smooth the top with a spatula.

5. Bake in the preheated oven for 60 minutes, or until a toothpick inserted into the center comes out clean.

6. While the cake is baking, prepare the rum glaze. In a saucepan, combine the butter, 1/4 cup water, and granulated sugar. Cook over medium heat until the sugar is dissolved.

7. Remove the glaze from the heat and stir in the remaining 1/2 cup of rum.

8. Once the cake is done, remove it from the oven and poke holes in the top using a skewer.

9. Pour the rum glaze over the warm cake, allowing it to soak in and around the cake.

10. Let the cake cool in the pan for 30 minutes before inverting it onto a serving plate.