"easiest and quickiest way"....
Follow mom to the grocery store. Watch her put baby in grocery cart. Follow through store. When mom reaches over to grab box of cereal (or candy bars), remove child from cart and run like hell.
Now, if you had asked about a legal way, you would have gotten a different answer. And before you ask, there is no "easiest and quickiest way" AND legal way. You would first have to prove unfit mother (CPS), then have a LOT of hearings and investigation to see if there are other, directly related "want-to foster", then go through a LONG foster program, then get a court order revoking the mothers rights... and so on.
Maybe you can just buy the baby from mom.