PreparationFor broccoli rabe pesto: Cook broccoli rabe in a large pot of boiling salted water until bright green, about 30 seconds; drain (reserve pot). Transfer to a bowl of ice water to cool. Drain. Squeeze out water; cut into 1" pieces. Combine broccoli rabe, garlic, oil, and red pepper flakes in reserved pot. Cook over low heat, stirring often, until broccoli rabe is very soft, 40-50 minutes. Let pesto cool slightly. Mix in Pecorino and honey. For assembly: Build sandwiches with bread, provolone, coppa, and broccoli rabe pesto. Brush a large skillet with oil; heat over mediumlow heat. Working in batches and brushing skillet with oil as needed, add sandwiches to pan, cover with foil, and place a heavy skillet on top. Cook until bread is toasted and cheese melts, 4-5 minutes per side (you can also use a lightly oiled panini press). DO AHEAD: Pesto can be made 3 days ahead. Cover; chill.
PreparationFor broccoli rabe pesto: Cook broccoli rabe in a large pot of boiling salted water until bright green, about 30 seconds; drain (reserve pot). Transfer to a bowl of ice water to cool. Drain. Squeeze out water; cut into 1" pieces. Combine broccoli rabe, garlic, oil, and red pepper flakes in reserved pot. Cook over low heat, stirring often, until broccoli rabe is very soft, 40-50 minutes. Let pesto cool slightly. Mix in Pecorino and honey. For assembly: Build sandwiches with bread, provolone, coppa, and broccoli rabe pesto. Brush a large skillet with oil; heat over mediumlow heat. Working in batches and brushing skillet with oil as needed, add sandwiches to pan, cover with foil, and place a heavy skillet on top. Cook until bread is toasted and cheese melts, 4-5 minutes per side (you can also use a lightly oiled panini press). DO AHEAD: Pesto can be made 3 days ahead. Cover; chill.