In a large pot of boiling salted water, cook tortellini about 2 minutes less than package instructions. Add peas; cook until pasta is al dente and peas are tender, 2 minutes more. Reserving 1 cup pasta water, drain. Set aside pasta and peas.
Melt butter in pasta pot over medium-low heat. Add garlic; cook until fragrant, about 1 minute. Discard garlic.
To pasta pot, add pasta and peas, Parmesan, and 3/4 cup reserved pasta water; season with salt and pepper. Toss to coat. Add more pasta water, if necessary, to thin sauce. Serve, topped with additional Parmesan if desired.
It's tasty, quick and kids love it.