Step 1Cut croissant into 1-inch cubes and bake at 250 degrees until dry enough to be processed into crumbs, about 20 minutes. Place in food processor and pulse to break bread into crumbs. Add brown sugar and butter and mix 1 more minute. Set aside.
Step 2Peel and cut tops from persimmons. Scoop out white core, creating small cavity.
Step 3Place persimmons in baking pan and add just enough water to cover base of pan. Cover persimmons with foil and bake at 350 degrees until persimmons are soft and fork-tender, 30 to 50 minutes, depending on ripeness of fruit.
Step 4When soft, drain excess water from pan and drizzle persimmons with 1/2 cup Muscat wine. Place persimmons back in oven without any foil and bake another 5 minutes. Set aside.
Step 5Bring remaining 1 cup Muscat wine to boil in saucepan and reduce to half. Set aside to cool. When cool, add creme frai^che.
Step 6Whip cream to soft peaks. Fold into creme frai^che-wine mixture. Refrigerate to chill.
Step 7About 10 minutes before serving, fill each persimmon with 1/2 tablespoon macadamia nuts and top with 1 tablespoon bread crumb-brown sugar mixture.
Step 8Broil persimmons until top browns, about 5 minutes. Watch closely so top does not burn. Once brown, remove from broiler and transfer to serving platter. Top baked persimmons with Muscat cream and garnish with mint leaves. Serve immediately.