*Cook's Note: To toast the almonds, arrange in a single layer on a baking sheet. Bake in a preheated 350 degrees F oven until lightly toasted, 8 to 10 minutes. Cool completely before using.
Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until tender but still firm to the bite, stirring occasionally, 8 to 10 minutes. Drain and place in a large serving bowl. Toss with 1/2 cup cheese.
In a large skillet, heat the oil over medium-high heat. Add the Brussels sprouts, onions, mushrooms, garlic, 1 teaspoon salt and 1/2 teaspoon pepper. Cook, stirring occasionally, until the onions are soft, 6 to 8 minutes. Add the creme fraiche, vegetable broth, lemon juice and lemon zest. Bring to a simmer and stir until the mixture forms a creamy sauce, about 2 minutes. Stir in 2 teaspoons salt and 1 teaspoon pepper.
Pour the sauce over the pasta, add the almonds and toss until coated. Sprinkle with the remaining cheese and serve.