Grease a 9 x 13-inch baking dish and add the bread cubes in an even layer. Scatter three-quarters of the toasted pecans over the bread.
Whisk the eggs, oat milk, coconut cream, maple syrup, brown sugar, vanilla, cinnamon, nutmeg, and salt until smooth. Pour the custard evenly over the bread.
Gently press the bread into the custard and let it soak for 30 minutes. Preheat the oven to 350 F while the bread absorbs the liquid.
Drizzle the melted plant butter over the pudding and scatter on the remaining pecans. Bake for 40 to 45 minutes, until puffed and golden with a softly set center.
Combine the maple syrup, coconut cream, plant butter, and salt in a small saucepan. Simmer over medium-low heat for 4 to 5 minutes, stirring frequently, until smooth and lightly thickened.
Let the bread pudding rest for 15 minutes so the custard settles without becoming dry.
Serve the bread pudding warm with the maple cream sauce spooned over each portion.