(not my photo - from Pinterest)
• 4 LARGE RUSSET POTATOES (ABOUT 12 OUNCES EACH)
• ½ CUP EXTRA-VIRGIN OLIVE OIL
• 2 TEASPOONS KOSHER SALT
• 1 SMALL ONION, FINELY CHOPPED
• 3 LINKS SWEET ITALIAN SAUSAGE WITHOUT FENNEL SEEDS, REMOVED FROM CASINGS (ABOUT 10 OUNCES TOTAL)
• 12 OUNCES MIXED MUSHROOMS (WHITE, CREMINI, SHIITAKE, OYSTER, ETC.), THINLY SLICED (ABOUT 4 CUPS)
• 1 CUP GRATED GRANA PADANO
• 3 TABLESPOONS CHOPPED FRESH ITALIAN PARSLEY
Preheat oven to 425 degrees. Halve the potatoes crosswise, and scoop out the flesh to make a boat or shell. Finely chop the flesh you’ve scooped out. In a large roasting pan, toss the scooped-out potatoes with ¼ cup of the olive oil, and season with 1 teaspoon salt.
Add the remaining ¼ cup olive oil to a large skillet over medium heat. When the oil is hot, add the onion, and cook until just softened, about 3 to 4 minutes. Add the chopped potato, and crumble in the sausage. Cook, stirring to break up the sausage, until the sausage is no longer pink, about 5 to 6 minutes.
Add the mushrooms, and season all with the remaining teaspoon of salt. Cook and stir until the mushrooms and chopped potato are just tender, about 10 to 12 minutes. Remove from heat, and scrape into a large bowl to cool slightly, about 5 minutes.
To the sausage mixture, stir in ½ cup of the grated cheese and the parsley. Fill the potato shells with the mixture, and arrange, filled side up, in the roasting pan. Sprinkle the tops with the remaining grated cheese. Pour ½ cup water into the bottom of the roasting pan, and cover the pan with foil, making sure not to touch the filling. Bake until potato shells are just tender, about 40 minutes. Uncover, and bake until tops are golden brown, about 25 minutes more.