Prep the bread. Cut the bread into 1-inch cubes and spread on a baking sheet. If it’s fresh, dry it in a 300°F (150°C) oven for 10–12 minutes until slightly crisp on the outside.

Grease the dish. Butter a 9x13-inch baking dish (or similar 3-quart dish). Add the bread cubes. Scatter in raisins or other add-ins if using.

Mix the custard. In a large bowl, whisk eggs, 2/3 cup granulated sugar, 1/4 cup brown sugar, cinnamon, nutmeg, salt, and vanilla until smooth. Whisk in 2 cups milk and 1 cup cream.

Soak the bread. Pour custard over the bread. Gently press to help it absorb. Let sit 20–30 minutes, stirring or pressing once or twice so all pieces get coated.

Preheat and dot with butter. Heat oven to 350°F (175°C). Dot the top with 2 tablespoons butter cut into small pieces.

Bake. Bake 40–50 minutes, until the top is golden and slightly crisp, and a knife inserted in the center comes out mostly clean with some custard. The center should be just set, not dry.

Make the whiskey caramel. While it bakes, add 1 cup granulated sugar to a heavy saucepan in an even layer. Cook over medium heat, undisturbed, until it melts around the edges. Stir or swirl gently as the sugar liquefies and turns deep amber. Remove from heat and carefully whisk in 3/4 cup heavy cream (it will bubble vigorously). Return to low heat and whisk in 6 tablespoons butter and 1/4–1/3 cup whiskey, plus a pinch of salt. Simmer 1–2 minutes until smooth and slightly thickened.

Adjust and finish. Taste the sauce. Add a touch more salt or whiskey if desired. For extra polish, strain the sauce to remove any lumps.

Serve. Let the pudding rest 10 minutes. Spoon warm squares into bowls and drizzle generously with warm whiskey caramel. Finish with a pinch of flaky sea salt if you like that sweet-salty hit.