Chocolate Amaretto Fudge

Pour 3/4 cup amaretto liqueur and 1/2 cup condensed milk into a large saucepan over medium-low heat. Add 3 cups sugar and stir until dissolved. Add 1/4 cup butter, semisweet chocolate chips, dark chocolate chips, and 1/2 cup white chocolate chips; stir until mixture is smooth and all chocolate has melted, about 5 minutes. Reduce heat to low; stir occasionally to prevent the mixture from burning.
Heat 3/4 cup sugar, 2 tablespoons condensed milk, and 2 tablespoons amaretto in a small saucepan over medium-low heat; cook and stir until sugar is dissolved, about 5 minutes. Add 1 1/2 cups white chocolate chips, 3 tablespoons butter, and red food coloring; stir until smooth and coloring is evenly distributed, about 3 minutes.
Remove both saucepans from heat. Pour dark chocolate mixture into a square 10-inch aluminum foil pan. Let sit for 1 to 2 minutes. Drop spoonfuls of the white chocolate mixture on top and swirl into dark chocolate layer with a butter knife or toothpick. Shake pan lightly to settle fudge. Refrigerate until firm, about 1 hour and 30 minutes. Cut into 1-inch squares.