In a large bowl, combine the flour, tarragon, salt, eggs, 1 cup water, and mustard. Stir vigorously until combined into a paste. If it's too thick, add just a bit more water until just smooth. Bring a large pot of salted water to a boil. Hold a colander over the pot and, using a rubber spatula, press the batter through the holes into the water. Boil for 3 minutes, then drain. Transfer the spaetzle to a baking dish.
For cheese sauce:
In a large saucepan, over medium-low heat, whisk together the Parmesan cheese, mascarpone, goat cheese, salt, and half-and-half to a simmer. Cook for 10 minutes. Whisk often to prevent burning. Pour the cheese sauce over the spaetzle and toss gently to coat. Dot the top with goat cheese and lay the prosciutto slices on top. Bake the spaetzle in the oven for 5 minutes to heat through. Set aside.
For Lambic Beer Jus:
Pour the beer into a saucepan and stir in the demi glace, sugar and a good pinch of salt. Bring to a simmer over low heat and cook until reduced by 1/3.
For the pork:
Raise the oven temperature to 450 degrees F. Preheat a grill or grill pan.
In a large bowl, combine the Cajun seasoning, cocoa, roasted garlic, sugar, and salt. Mix until well combined. Dredge the pork into the spice rub and grill for 2 minutes on each side. Transfer the pork to a baking sheet and finish in the oven for about 10 minutes (5 minutes more for 2 tenderloins), or until cooked to medium and the internal temperature reaches 155 degrees F. While the pork is finishing in the oven, slice the leeks into 1/4-inch rounds and rinse in a bowl of cold water to remove excess dirt. Drain and dry well. Fill a large, deep, heavy-bottomed saucepan, halfway with oil and heat over medium-high heat to 350 degrees F. Toss the leeks in flour and a pinch of salt. Deep fry the leeks in the hot oil until golden brown. Drain on paper towels. Slice the pork loin and spoon the beer sauce over top and top with crispy leeks. Serve the spaetzle on the side.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.