Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or cooking spray and set aside.

Place the bread cubes in a large mixing bowl. If your bread is fresh, toast the cubes in the oven for 10 minutes first to dry them out slightly.

In a separate large bowl, whisk together the milk, heavy cream, eggs, sugar, cinnamon, vanilla extract, and salt until the sugar is mostly dissolved and the mixture is smooth.

Pour the custard mixture over the bread cubes and gently fold with a spatula until every piece is coated. Add the raisins and mix to distribute evenly. Let the mixture sit for 30 minutes at room temperature, pressing down occasionally so the bread absorbs the custard.

Transfer the soaked bread mixture to the prepared baking dish, spreading it evenly. Drizzle the melted butter over the top.

Bake for 45-50 minutes, until the top is golden brown and crispy, and the center is set but still slightly jiggly. A knife inserted in the middle should come out mostly clean.

Remove from the oven and let cool for 10 minutes before serving. The pudding will firm up slightly as it rests.