Fill a large pot with water and bring to a boil. Add the broccoli rabe and cook for 5 minutes; drain thoroughly and set aside.
In a large skillet over medium-high heat, melt the butter. Allow the butter to bubble, swirling the pan frequently, until it begins to turn golden brown and takes on a nutty smell.
Turn the heat down to medium and add the garlic and crushed red pepper flakes to the brown butter. Cook for 90 seconds or until the garlic starts to turn lightly brown.
Add the chicken to the pan, stir well, and season with the salt. Allow the chicken to cook until it’s lightly golden on one side, then turn over and continue to cook, stirring frequently, for 5-7 minutes.
In a small bowl, whisk together the balsamic vinegar and honey. Pour over the chicken.
Arrange the cooked broccoli rabe on top of the chicken, then cover the pan with a tight-fitting lid and let it cook, shaking occasionally, for 2-3 minutes. Remove the lid, stir well, and remove from the heat.
Add the lemon juice and parsley and serve warm over couscous or rice.