How extracting a method can make a function go from tail recursive to just regular recursive. There's a few more ways too.

notTailRecursive.scala

def bar(value: Int) = foo(Some(value / 3))

def foo(value: Option[Int]): Option[Int] = value match {
  case Some(v) if (v % 2 == 0) => bar(v)
  case Some(v) => Some(v)
  case None => None
}

tailRecursive.scala

def foo(value: Option[Int]): Option[Int] = value match {
  case Some(v) if (v % 2 == 0) => foo(Some(v / 3))
  case Some(v) => Some(v)
  case None => None
}