Bring a large pot of water with a large pinch of salt to a boil. Halve the leeks lengthwise, then thinly slice. Place the leeks in a colander and rinse under water to remove any sand. Mince or grate the garlic. Strip the thyme leave off the stem, then roughly chop the leaves.

Add the pasta to the boiling water and cook 8-10 minutes, until al dente. Drain.

Heat a drizzle of oil in a large pan over medium heat. Add the leeks to the pan and cook, tossing, 5-6 minutes, until soft and slightly caramelized. Add the mushrooms and another drizzle oil to the pan and cook, tossing, 4-5 minutes, until soft. Add the garlic and thyme to the pan and cook 30 seconds, until fragrant. Season with salt and pepper.

Add the stock concentrate and 1/2 cup water to the pan and stir to combine. Remove pan from heat, then stir in the cream cheese, mixing thoroughly to combine. Season with salt and pepper.

Return pan to medium heat and carefully toss in the drained pasta until thoroughly coated in sauce. Stir in 1 tablespoon butter and half the Parmesan cheese and toss to combine. Season with salt and pepper.

Serve pasta garnished with the remaining Parmesan cheese and enjoy!