Greens Mac and Cheese

Ingredients

• 3 tablespoons unsalted butter
• 1 large leek—trimmed, halved, washed and sliced
• 3 garlic cloves, peeled and sliced
• 14 ounces broccolini, stalks sliced and florets reserved
• ½ bunch fresh thyme (½ ounce), leaves stripped
• 2 tablespoons all-purpose flour
• 4 cups milk
• 16 ounces dried macaroni
• 1 ounce Parmesan cheese, grated
• 5 ounces sharp cheddar cheese, grated and divided
• 3½ ounces baby spinach
• Kosher salt and freshly ground black pepper
• 1¾ ounces slivered almonds