Prepare fettuccine according to package directions. Drain, but save about ¼ cup of the cooking liquid for the sauce.
While the fettuccine is cooking, heat olive oil and garlic in a large skillet over medium-high heat. Cook, stirring occasionally, for 1 minute or just until garlic starts to turn golden brown.
Add mushrooms and onion powder. Season with salt and black pepper, to taste, and stir to combine. Cook, stirring occasionally, until mushrooms start to release liquid and change color, approximately 4-5 minutes.
Add reserved pasta cooking liquid and vegetable broth and continue cooking until liquid is reduced by half.
Stir in half the fresh basil and Parmesan cheese and cook until the cheese is melted, about 1-2 minutes.
Pour sauteed mushroom mixture over the cooked fettuccine pasta. Toss to combine. Serve immediately with remaining fresh basil and Parmesan cheese.