In a large skillet heat the olive oil over medium-high heat. Add the shallot, garlic and crushed red pepper; cook unitl the shallot is softened, 2 to 3 minutes. Add the barley and cook, stirring for 1 minute. Add the wine and cook until most of the liquid is absorbed, about 2 minutes. Add the chicken broth, 1 1/2 cups water and 1/2 teaspoon salt and black pepper; bring to the boil. Lower the heat and simmer, covered, until the grains are tender but chewy, about 30 minutes.
Stir in the spinach, mascarpone, grated parmessan and grated lemon peel; season with salt and pepper. Serve immediately, sprinkled with thinly sliced lemon peel and shaved parmessan.