Cut your cinnamon rolls into roughly 1-inch cubes to create bite-sized pieces that will soak up the custard but still hold their shape.
In a large bowl, whisk together whole milk, eggs, granulated sugar, vanilla extract, ground cinnamon, and salt until smooth and sugar is somewhat dissolved.
Place the cubed cinnamon rolls in your baking dish. Sprinkle chopped pecans and raisins evenly over the top. Pour the custard mixture over everything, gently pressing the cinnamon rolls down to help them absorb the liquid. Let it sit for 10-15 minutes to soak.
Preheat your oven to 350°F (175°C). Brush the melted butter over the top of the pudding to encourage a golden crust. Bake uncovered for about 40-45 minutes or until the custard is set and the top is golden brown with a slight jiggle in the center but no liquid custard.
Remove from the oven and allow to cool slightly. Dust with powdered sugar right before serving. Enjoy warm or at room temperature.