Preheat oven to 350°F (175°C). Generously butter a 7×11 inch ceramic or glass baking dish.

Cut the bread into large cubes, around 1.5–2 inches. Place them in the prepared dish in a loose, uneven layer.

In a medium saucepan, whisk together eggs, yolks, milk, cream, sugar, vanilla, and butter. Cook over medium-low heat, stirring often, until the butter melts and everything is well combined. Do not let the mixture boil or thicken.

Pour most of the custard mixture over the bread in the dish, saving about 1.5 to 2 cups. Gently press the bread down so it absorbs the liquid evenly.

Bake the pudding for 35–40 minutes, until the top is golden and the center is just set with a slight jiggle.

While it bakes, return the reserved custard to the stove over low heat. Stir constantly until slightly thickened and it coats the back of a spoon. Strain if needed to remove any curdled bits. This will be your crème anglaise.

Serve the bread pudding warm with a drizzle of the vanilla sauce and a dusting of powdered sugar, if desired.