Cauliflower Mushroom Mac and Cheese Gratinée

Name: Cauliflower Mushroom Mac and Cheese Gratinée
Ingredients: 1/2 large head of cauliflower; 3 cloves of garlic; 2 tablespoons olive oil; 1/2 pound matsutake or other wild mushroom; 10 ounces penne pasta; 1 cup fine breadcrumbs; 2 tablespoons butter; 2 tablespoons flour; 1 and 1/2 cups milk (any fat content); 1 cup grated gruyere cheese; salt and black pepper to taste