Preheat the oven to 350F. Cut four slices of bread into 1/2-inch dice, and spread the diced bread on the bottom of a casserole dish. Sprinkle the raisins on top of the bread cubes and pour any remaining liquid over the bread.
Whisk the yolks, vanilla paste and sugar in a large bowl until combined. Bring the milk and cream to a boil in a heavy saucepan over high heat and pour the hot mix onto the egg yolks, whisking constantly. Pour this warm egg mixture over the bread, making sure all of the bread is coated, and set aside the coated bread for 20 minutes to allow the egg mixture to soak into the bread.
Remove the dish from the oven and roasting tray, and sprinkle with the extra sugar. Broil or use a crème brule torch to caramelize the sugar. Sprinkle with the toasted sliced almonds and dust with powdered sugar.