Pasta Shells with Spring Greens, Mâche, and Prosciutto

• 2 tbsp unsalted butter
• 2 tbsp extra-virgin olive oil, plus more for serving
• 1

Melt the butter with the oil in a large skillet over low heat. Add the shallot and season with coarse salt and pepper. Sauté over low heat, for 7 to 8 minutes, until soft but not browned. Add the wine, increase the heat, and boil for about 3 minutes. Add the stock and bring to a boil.

Remove from the heat and set aside.

Bring a large saucepan of salted water to a boil and add th