Holy cow! A recently demoted Brooklyn priest whose church finances are under federal investigation has an impressive real estate portfolio worth more than $2 million, including a house in the Hamptons and a pricey waterfront condo in Florida, a review of records by The Post reveal. Monsignor Jamie Gigantiello, who had his pastoral duties yanked at Our Lady of Mount Carmel — Annunciation of the Blessed Virgin Mary last week even peddled a $2,000-a-week timeshare on the resort island of St. Martin on Facebook in October, the review found.