Preheat oven to 200° with rack in lowest position. Bake bread in a large rimmed pan until crisp, 40 to 45 minutes. Let cool.
Meanwhile, peel the top quarter of each apple and, using a melon baller, scoop out stem, core, and enough of inside so that walls of apple are about 1/2 in. thick (don't break through bottoms). If needed, trim bottoms slightly so apples sit upright.
In a large bowl, whisk sugar, molasses, butter, eggs, half-and-half, ginger, vanilla, and nutmeg to blend. Increase oven to 325°. As it heats, bake pecans in a shallow pan until golden, 10 to 12 minutes.
Add bread and cranberries to molasses mixture; toss to coat. Let stand, stirring occasionally, until two-thirds of liquid is absorbed, 12 minutes. Stir in pecans.
Generously stuff apples with bread mixture, mounding it. Set in a 9- by 13-in. baking dish plus a smaller shallow dish.
Bake until each apple is very tender when pierced, about 1 hour; check after 40 minutes and tent loosely with foil if they're getting dark. Serve warm in shallow bowls with ice cream and caramel sauce.
Make ahead: Prepare through step 5 and chill airtight up to 1 day. Bring to room temperature (2 1/2 hours) before baking.