Preparation

• Heat the milk in a 2-quart saucepan over medium heat until beginning to steam, about 3 minutes. Reduce the heat to low and keep warm without simmering.
• In a heavy-duty 4-quart saucepan, melt the sugar over medium heat, stirring occasionally at first and then less and less as the sugar melts, and then cook until amber, about 4 minutes. Reduce the heat to low. Carefully whisk the hot milk into the caramel in a thin, steady stream. Cook, whisking constantly, until the caramel dissolves again. Remove from the heat and whisk in 1-1/2 cups of the cream. Keep warm.
• Whisk the egg yolks, cornstarch, and 1 tsp. of the vanilla in a large bowl until smooth. Whisk in about half of the hot caramel mixture. Whisk this mixture back into the saucepan. Cook over low heat, stirring constantly with a wooden spoon, until it reaches 170°F on an instant read thermometer and can thickly coat the back of the spoon, about 5 minutes.
• 将混合物通过细网筛将其过滤成干净的碗。冷藏直至彻底冷藏，至少4小时或最多2天，覆盖塑料包裹后冷。
• Meanwhile, put the chocolate, butter, and remaining 1/2 tsp. vanilla in a large bowl. Set aside.
• 用中火将剩余的1/3杯奶油，枫糖浆，红糖和可可粉和可可粉搅拌，直到糖溶解为止。不断搅拌，小火煮5分钟以融合口味。
• Pour the cream mixture over the chocolate mixture. Let sit for 1 minute, then whisk until smooth. Cool at room temperature for at least 30 minutes or up to 1 day, covering with plastic once cooled.
• 根据制造商的说明，将焦糖冰淇淋混合物搅拌在冰淇淋机中，直到它是软冰淇淋的一致性。
• Stir the fudge until smooth. (If hardened, soften over a bowl of hot water, stirring until pourable but not hot.) Spread about a quarter of the caramel ice cream in a 9×5-inch loaf pan. Spread 2 Tbs. of the fudge over the frozen custard. Repeat twice and end with a layer of ice cream. Serve or cover and store in the freezer for up to 1 week.
• Reserve the remaining fudge for serving.