Turn on the oven’s broiler and line a baking sheet with foil. Toss the broccoli with oil, salt, and pepper then spread over the prepared baking sheet. Broil for 5-10 minutes (this will depend on your broiler’s strength), or until lightly charred. Alternatively, you can bake in a 500ºF oven for 10 minutes or so.

While the broccoli cooks, prepare the sauce. Combine yolks, lemon juice, zest, and a pinch of salt in the bottom of a jar that barely fits the head of an immersion blender. Melt the butter in a separate glass jar in the microwave until hot (or on the stovetop in a small saucepan). Blend the yolk mixture by running the immersion blender in the bottom of the jar. Without moving the blender head, slowly pour the melted oil in while blending constantly. An emulsion will form. Taste and adjust with more salt and pepper. Serve over roasted broccoli.