Heat oven to 350°F. Grease a 9×13-inch baking dish with 1 tbsp butter.
Toast pecans and a handful of coconut on a sheet pan for 5–7 minutes, until fragrant. Cool slightly.
Whisk eggs and yolks with granulated sugar, 1/2 cup brown sugar, salt, cinnamon, and nutmeg until smooth.
Stream in milk, 1 cup cream, and 2 tsp vanilla. Whisk until the custard is well combined.
Combine bread cubes with 1 1/4 cups coconut and about 1 cup toasted pecans. Spread evenly in the dish.
Pour custard over bread. Press gently to submerge. Rest 15 minutes to soak.
Bake 45–55 minutes, tenting with foil if browning fast, until the center is just set but still custardy.
Make praline sauce: Melt 6 tbsp butter with 2/3 cup brown sugar over medium heat until bubbling.
Whisk in 1/3 cup cream and 1 tsp vanilla. Simmer 2–3 minutes until glossy; stir in remaining pecans.
Spoon warm praline over the pudding. Sprinkle extra coconut. Broil 1–2 minutes to toast, if desired.