In a large, deep skillet, heat the olive oil until shimmering. Add the pancetta and cook over moderately high heat, stirring occasionally, until golden, 4 to 5 minutes. Add the garlic, anchovies and crushed red pepper and cook until the garlic is softened and beginning to brown, about 2 minutes. Add the escarole in large handfuls, tossing until wilted, 1 to 2 minutes. Add the chicken stock, cover and cook for 1 minute. Uncover and cook until the liquid is nearly evaporated and the escarole is tender, 2 to 3 minutes. Season with salt and pepper and serve.