Add the potatoes to a large stock pot filled with water. Salt the water generously (this will add a flavor to the potatoes while they are cooking – like you would with pasta). Bring the water to a boil. Boil the potatoes until tender. Meanwhile, in a very Portuguese way of using everything and not wasting, bring another small pot of water to a boil with the shrimp shells, and tablespoon of salt, the whole parsley stems, bay leaf, 1/2 white onion, 1 teaspoon of black pepper. Boil for 30 minutes. Drain and reserve 1/3 cup for sauteing and save the rest of the water to use as stock in soup. Meanwhile season the shrimp the with the dried spices, a dash each of salt and pepper, 1 tablespoon olive oil and 1/2 the wine. In a large saute pan cook 1 garlic clove and 1/2 of the shallot in 1 tablespoon olive oil, when soft add the mushrooms and the parsley cook for another 2-3 minutes until warm and slightly caramelized. Keep warm until ready to serve. When the potatoes are soft, drain and add them back to the pot. Drizzle in olive oil, starting with out 1/3 cup, whisking as you drizzle. Depending on the texture of your potatoes you may need to add up to 1/2 or even more, but you want them to almost have a yellow-green hue and be able to taste the herbal notes married with the truffle, without being runny. Fold in the truffle paste or truffle salt with 1/2 tablespoon pepper and salt, to your taste. Keep warm until ready to serve. Heat 1 more tablespoon of oil and saute the remaining garlic and shallot and cook until just soft. Add the wine and stock. Reduce by 3/4. Toss in the shrimp and quickly saute for 2-3 minutes until pink – be careful not to over cook. Plate by placing a large spoonful of potatoes in the center of a plate place a few mushrooms around the plate. Add three or four shrimp to the top of the potatoes and drizzle with the finishing oil and an extra sprinkle of parsley.