Step 1Cut the peaches in half and remove the pits. Place the sugar and Muscat in a small saucepan and cook over very low heat just until the sugar has melted, 2 to 3 minutes.
Step 2Place peaches cut side down in a glass baking dish and pour the Muscat mixture over the top. Cover with plastic wrap and set aside to macerate for one hour.
Step 3Place the almonds on a baking sheet and bake in a 350-degree oven until golden, about 5 to 7 minutes. Set aside to cool.
Step 4Heat the barbecue grill or grill pan to medium heat. Using a slotted spoon, remove the peaches from the Muscat mixture and place on a baking pan lined with paper towels. Pour the Muscat mixture back into the saucepan and cook over medium heat until the liquid is reduced to one-fourth cup, about 15 minutes.
Step 5Pat the peach halves dry and brush them lightly with oil. Place them on the grill, cut side down, and cook for 3 to 4 minutes, or until pale golden grill marks appear, then turn over and grill for a few more minutes, just until a knife inserted in the center goes in easily.
Step 6Remove the peaches to a serving platter. Place a scoop of vanilla ice cream in the center of each peach, drizzle the reduced Muscat over the ice cream, sprinkle with the toasted almonds and serve immediately.