Preheat oven to 350°F (175°C). Generously grease a 9x13-inch baking dish with butter or cooking spray.
Cut the panettone into 1-inch cubes using a sharp serrated knife. Spread the cubes in an even layer in the prepared baking dish and sprinkle the golden raisins evenly over the top. Set aside.
In a large mixing bowl, whisk the eggs until well beaten and slightly frothy. Add the heavy cream, whole milk, granulated sugar, vanilla extract, almond extract, and salt. Whisk until completely combined, smooth, and the sugar begins to dissolve.
Pour the custard mixture evenly over the panettone cubes. Gently press down on the bread with a spatula to ensure all pieces are submerged. Let sit for 10-15 minutes so the panettone absorbs the liquid, then press down gently once more and sprinkle the sliced almonds evenly over the top.
Bake on the center rack for 40-45 minutes, until the top is golden brown and the custard is set. The center should still have a slight jiggle when shaken gently, and a knife inserted in the center should come out mostly clean with just a bit of custard. If browning too quickly, cover loosely with aluminum foil.
Remove from the oven and let cool for 10 minutes before serving.
While the bread pudding bakes, combine the heavy cream and butter in a small saucepan over medium heat. Stir occasionally until the butter melts completely.
Add the powdered sugar and whisk continuously until smooth and the sugar has dissolved. Bring to a gentle simmer, stirring constantly.
Remove from heat and stir in the amaretto liqueur. The sauce will thicken slightly as it cools. Keep warm until ready to serve, or reheat gently before drizzling over the bread pudding.