in boiling salt water, cook tortellini about 2 minutes less than pkg directions. add peas; cook until al dented & peas are tender, 2 minutes more. reserve 1 cup of pasta water, drain. set aside pasta & peas.

melt butter in pasta pot over med- low heat. add garlic; cook until fragrant about 1 minute. discard garlic.

to pasta pot, add pasta, peas, parm, & 3/4 cup of pasta water; season with S&P. toss to coat. add more water, if needed, to thin sauce