Heat the oven to 350°F and butter a 9-by-13-inch baking dish.

Place the bread cubes in a large bowl, pour over the milk, and let stand for 10–15 minutes, stirring once or twice, until thoroughly softened.

Whisk together the eggs, granulated sugar, brown sugar, melted butter, vanilla, cinnamon, nutmeg, and salt.

Pour the egg mixture over the soaked bread, then fold in the raisins and optional pecans.

Transfer the mixture to the buttered dish and let it stand for another 10–15 minutes so the custard absorbs evenly.

Bake uncovered for 45–55 minutes, until the center is set but still slightly soft and moist. A knife inserted near the center should come out mostly clean.

Rest the pudding for 10–15 minutes before serving.

For the sauce, melt the butter in a small saucepan over medium-low heat. Whisk in the sugar and cream, heating gently until the sugar dissolves and the mixture is hot without reaching a hard boil.

Whisk the egg yolk in a bowl, slowly whisk in several tablespoons of the hot sauce to temper it, then return the tempered mixture to the saucepan. Cook over low heat for 2–4 minutes, stirring constantly, until slightly thickened; do not boil.

Remove the sauce from the heat and stir in the vanilla and optional bourbon. Spoon the warm sauce over individual portions.