Put a large pot of water on to boil for cooking pasta. Also bring about 1 inch of water to a gentle simmer in the bottom of a double boiler (see Equipment Tip).

Heat oil in a medium nonstick skillet over medium heat. Add prosciutto (or Canadian bacon) and cook, stirring often, until heated through, about 2 minutes. Add garlic and crushed red pepper; cook, stirring, for 30 seconds. Remove from heat.

Whisk eggs, broth and pepper in the top of the double boiler to combine. Set over the simmering water in the bottom of the double boiler and cook, whisking constantly in a slow, steady, figure-eight motion, until the sauce steams and thickens enough to coat a metal spoon, 5 to 7 minutes. The sauce may have a few small curdles. Remove the top pan from the heat and whisk the sauce rapidly so it does not continue to curdle.

Meanwhile, cook pasta in the boiling water, stirring often, for 5 minutes. Drop in broccolini (or broccoli rabe) and cook until the pasta is tender but firm, 4 to 6 minutes more. Drain and place in a large bowl. Add the egg sauce, the prosciutto (or bacon) mixture and cheese; toss to coat well. Season with salt, if desired.

Equipment tip: No double boiler? Improvise by setting a large stainless-steel bowl over a pan of simmering water.