Prep the dried fruit. Soak the chopped dried fruit overnight in marsala, sweet sherry, or port. Drain well through a fine-mesh strainer, pressing to extract the maximum amount of liquid. Discard, save, or drink the wine and set fruit to the side.
Preheat oven to 350°F.
Prep the butternut squash. Pierce deeply all over with a paring knife. Microwave on High, uncovered, for 3 minutes to soften the skin. Allow to cool for at least 5 minutes. Slice off the stem and base ends and discard. Using a sharp vegetable peeler, peel the squash until only orange shows all around. Cut in half crosswise, then cut each half lengthwise. Scoop out the seeds and strings. Cut into 1" cubes until you have 1 ¼ pounds.
Cook the squash. Transfer squash cubes to Instant Pot with 1 cup of water. Secure lid, close pressure valve, and pressure cook on High for 4 minutes. Perform a quick release immediately. Press Cancel to turn off warming function.
Prepare the puree. Transfer squash cubes to a colander and drain well. Return to Instant Pot insert. Mash squash cubes with flour and sugar using a potato masher. Stir in butter until melted. Add half & half, eggs, salt, cinnamon, and nutmeg. Puree with an immersion blender until velvety smooth. Stir in the dried fruit and orange peel.
Bake the custard. Pour squash mixture into an ungreased 8"x8" baking dish. Transfer to oven and bake until center is set, about 45 – 55 minutes. Allow to cool slightly and serve.
