Prepare ingredients: quarter the potatoes, then slice each quarter into 1/4-inch (6 mm) thick pieces; separate the broccoli into florets; measure the green peas; chop the leek (4 oz); mince 2–3 cloves garlic; measure tomato paste (1 Tbsp), dried rosemary (1/2 tsp), olive oil (1 Tbsp), nutritional yeast (3 tsp), salt (1/4 tsp), and black pepper (1/8 tsp). Have 4 cups hot water ready.

Heat a Dutch oven over medium heat. Add 1 Tbsp olive oil.

Add the chopped leek and cook, stirring, for 1 minute.

Add the minced garlic and cook, stirring, for 2 minutes more.

Add the sliced potatoes, 1 Tbsp tomato paste, 1/2 tsp dried rosemary, 1/4 tsp salt, and 1/8 tsp black pepper. Stir to combine.

Pour in 2 cups of the hot water, stir, cover the pot, and cook for 10 minutes, until the potatoes are soft when pierced with a fork.

Uncover and mash the potatoes in the pot with a fork, leaving some larger chunks so the mixture becomes a creamy sauce with pieces of potato.

Add the remaining 2 cups hot water and the 9 oz pasta to the pot. Stir to combine, bring to a simmer, then cover and cook for a total of 10 minutes, stirring occasionally to prevent sticking.

With about 2 minutes of pasta cooking time remaining, add the broccoli florets (5 oz), green peas (2 oz), and 3 tsp nutritional yeast. Stir, cover, and finish cooking until the pasta is tender and the vegetables are heated through.

Remove from heat, give everything a final stir to combine, and serve.