The Menendez brothers are going to spend at least one more Thanksgiving behind bars ... and TMZ has the cranberry sauce on what their gobble-gobble day is going to look like.
A source in the California Department of Corrections tells TMZ ... Lyle and Erik -- who've been in prison nearly 35 years for the double murder of their parents -- will feast on turkey slices, mashed potatoes, greens, and peach pie this Thanksgiving.
Also happening at the Richard J.