In a 1 qt or small pot, heat the rum to a simmer and using a long candle lighter, light the rum on fire (keep your head back away from the pot when you light it. If flame is too high, turn down heat or cover to extinguish). Continue to cook for about 1 minute and remove from heat (the goal is to cook off the alcohol). Add the raisins to the pot (they should be covered by the cooked rum) and let rehydrate until needed.
Preheat your oven to 400. Next, peel and uniformly dice the sweet potato, squash, and celeriac or parsley root. Fine chop the onion and garlic. Over medium-high heat, heat a large Dutch oven or deep-sided pan with a few tablespoons of oil. Add the onion and sweat for a few minutes, next add the garlic. Cook garlic for another minute (careful not to burn).
Add the chopped vegetables making sure not to completely over crowd the pan as you want to get a little bit of color on winter vegetables. Sauté until the vegetables begin to soften, about 5-8 minutes. Next stir in lemon zest, strained raisins, herbs, hickory nuts and season with salt to taste.
Combine the breadcrumbs and biscotti together and sprinkle over top of the vegetables. Place into the oven uncovered for about 7 minutes, or until the breadcrumbs start to brown. Remove from oven and enjoy.