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.
• 应变的混合物倒入细网筛a clean bowl. Refrigerate until thoroughly chilled, at least 4 hours or up to 2 days, covering with plastic wrap once cold.
• Meanwhile, put the chocolate, butter, and remaining 1/2 tsp. vanilla in a large bowl. Set aside.
• Whisk the remaining 1/3 cup cream, maple syrup, brown sugar, and cocoa powder in a 3-quart saucepan over medium heat until the sugar dissolves. Whisking constantly, simmer for 5 minutes to meld the flavors.
• 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.
• Churn the caramel ice cream mixture in an ice cream machine according to the manufacturer’s instructions until it’s the consistency of soft-serve ice cream.
• 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.