Pour 2 cups low-sodium chicken or vegetable broth into the inner pot. Add 2 teaspoons minced garlic, 1/2 teaspoon kosher salt, and 1/2 teaspoon black pepper and stir to combine.
Layer 8 ounces fettuccine noodles broken in half into the broth. Arrange them in a crisscross pattern so they sit evenly and are less likely to stick together.
Scatter 1 tablespoon cubed unsalted butter over the noodles, then pour 1 cup heavy cream evenly over the top.
Secure the lid and set the pressure valve to sealed. Cook on high pressure for 6 minutes using the Manual/Pressure Cook setting.
When cooking finishes, allow a natural pressure release for 5 minutes. After 5 minutes, carefully perform a controlled quick release by slowly turning the valve to venting until the float drops, then open the lid.
Stir the pasta to combine with the sauce. It's normal for some liquid to remain; the noodles will absorb it as they rest.
Stir in 1/2 cup freshly grated Parmesan cheese, then replace the lid and let the pasta sit for a couple of minutes to allow the cheese to melt into the sauce.
Serve immediately, adding extra Parmesan if desired.
