Prepare 10-cup Bundt pan. Grease generously with melted butter, ensuring all nooks and crannies are well-coated. Then, dust with all-purpose flour, tapping out any excess. Set aside.

Preheat your oven to 350°F (175°C) and position the oven rack in the center.

In a medium saucepan, bring the prunes and water to a boil. Once boiling, cover and turn off the heat. Let the prunes sit, covered, for about 10 minutes to soften.

In a large bowl, whisk together the flour, baking soda, baking powder, and salt.

In a stand mixer or hand mixer, beat the sugar and eggs together until smooth and well combined.

Slowly add the canola oil, mixing until fully incorporated.

Blend in vanilla.

Using a hand blender or food processor, blend the softened prunes until smooth (a few chunks are fine).

Stir the molasses into the prune puree.

On low speed, add the dry flour mixture to the sugar-egg-oil mixture in thirds, alternating with the prune-molasses puree. Begin and end with the dry flour mixture.

Once fully combined, fold in the chopped walnuts using a spatula.

Pour the batter into the prepared Bundt pan and smooth the top.

Bake for 50-55 minutes, or until a toothpick inserted into the center comes out mostly clean.

Let the cake cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.

Once the cake has cooled, dust with icing sugar before serving.