Preheat your oven to 350°F (175°C). Generously butter a 9x13-inch baking dish and set aside.
Spread the bread cubes in the prepared baking dish in an even layer. If your bread is very fresh, toast the cubes on a baking sheet for 8-10 minutes until slightly dried but not browned.
In a large bowl, whisk together the whole milk, heavy cream, eggs, sugar, vanilla extract, almond extract, cinnamon, and salt until the sugar dissolves and the mixture is smooth, about 1 minute.
Pour the custard mixture evenly over the bread cubes, pressing down gently with a spatula to ensure all pieces are submerged. Let stand for 15 minutes, pressing down occasionally so the bread absorbs the custard.
Drizzle the melted butter over the top and sprinkle with the toasted sliced almonds, distributing them evenly across the surface.
Bake for 45-50 minutes until the top is golden brown and the center jiggles only slightly when gently shaken. A knife inserted near the center should come out mostly clean with just a few moist crumbs.
Remove from the oven and let rest for 10 minutes before serving. The custard will continue to set during this time, making it easier to slice into neat portions.