Rather than rely on a bunch of descriptives to tell you just how delicious this bread pudding is, we'll just say this: Toddy's most dedicated healthy eater - someone who regularly snacks on raw bell peppers and undressed lettuce - left this review: "Nomnomnomnom, great crisp top and custardy inside. DEFINITELY making this one."
Remove and discard crust from bread, and cut enough bread into 1/2-inch cubes to measure 6 cups. In a large baking pan, dry out the bread, uncovered, at room temperature for 12 hours. (For a faster alternative, you can also dry out the bread in a 250°F oven for 1 hour.) Butter an 8x8-inch pan.
Chop walnuts and toast them in a saute pan, being careful not to burn them. Set aside the walnuts and allow them to cool. In a bowl, toss together bread, half of the walnuts, and all of the butterscotch chips, and transfer the mixture to a buttered pan. In a small saucepan, heat 1 cup milk until it begins to boil. Remove pan from heat, and add cold brew coffee concentrate and remaining cup of milk; stir to combine.
In a bowl, whisk together eggs, sugar, and salt, then whisk in coffee mixture until combined well. Pour custard slowly and evenly over the bread mixture. Chill pudding, covered, at least 1 hour and up to 1 day.
Preheat oven to 350°F. Sprinkle the remaining walnuts evenly over pudding. Cut butter into bits and dot the pudding with it. Bake bread pudding in the middle of the oven until bubbling and golden, between 50 and 60 minutes. Serve pudding warm or at room temperature.
Makes 8 servings