In a deep skillet or large saucepan, bring 3 inches or water to a boil. Salt the water, add the broccoli rabe and cook for 3-4 minutes. Drain well.
In a large skillet, heat the EVOO, 4 turns of the pan, over medium heat. Add the anchovies, cover the pan with a splatter screen or lid, and shake until the anchovies begin to break up. Reduce the heat a bit, uncover and stir until anchovies melt into the oil. Add the garlic and red pepper flakes, and stir for 1 minute. Add the chicken stock and heat through. Just before serving, add the broccoli rabe to the pan and heat through.
Transfer to a serving platter and top with ricotta salata.