A new and distinct variety of nectarine tree (Prunus persica sub species nuciperisica), denominated varietally as `Burnectwentythree`, and which produces an attractively colored white-fleshed, non-melting, sub-acid, saucer-shaped, clingstone nectarine, which is mature for harvesting and shipment approximately June 12 to June 20 under ecological conditions prevailing in the San Joaquin Valley of central California.