Preheat the oven to 400 F.Get a sheet pan. On a cutting board, cut the shallot into thin wedges. Cut the broccolini into 3-inch long florets and then slice the stemsin 3/4-1/2 inch pieces, discarding the bases.Place the shallots and broccolini on the sheet pan, drizzle with olive oil, sprinkle with salt and red pepper flakes and toss well to coat.
Roast for 20-25 minutes to brown the tips of the broccolini. Transfer to a platter and serve.