2 tablespoons olive oil
8 ounces uncooked Italian sausage, casings removed
1/2 teaspoon kosher salt
1 1/2 cups water, divided
1 (24-ounce) jar marinara sauce
8 ounces dried ziti or penne pasta
8 ounces ricotta cheese
1 cup shredded part-skim mozzarella cheese
Turn on an electric pressure cooker or Instant Pot to sauté. Once heated, add the olive oil, followed by the sausage. Break up the sausage into large pieces with a wooden spoon and season with the salt. Cook, stirring and breaking the sausage into smaller and smaller pieces, until cooked through and no longer pink, about 5 minutes.
Turn the pressure cooker off. Add 1/2 cup of the water and scrape the bottom of the pot to loosen any browned bits. Add the marinara and stir to combine well. Scatter the pasta over the sauce-sausage mixture in an even layer. Do not stir from this point on.
Rinse the pasta sauce jar with the remaining 1 cup water (pour the water into the jar, cover, and shake gently) and then pour the water over the pasta. Remember — no stirring here.
Seal the pressure cooker. Use the manual setting to set the pressure cooker to cook for 8 minutes under HIGH pressure. It will take 10 to 12 minutes to come up to pressure.
When the cook time is done, immediately do a quick release of the pressure. Turn the pressure cooker off. Open it, add the ricotta, and stir quickly to combine. Sprinkle with the mozzarella. Cover the pressure cooker again and let sit for 3 minutes for the cheese to melt and the sauce to thicken. Serve immediately.