I’ve tried it. I love roasted Brussels Sprouts and when I saw a package in the frozen food section, I thought I’d stumbled onto a marvelous shortcut.
Uh, no. I’d stumbled into a horrible, soggy, neverland. No wonder people claim not to like them; they were all but inedible.
Now, I’m a big fan of the frozen Brussels Sprouts. I steam them in the microwave with a teaspoon of water and a tablespoon of butter, and they are certainly not inedible… and least of all a “a soggy neverland”. Are they the same as fresh… no, but I bet, if I were to thaw those frozen Brussels Sprouts, drain them, cut them in half and leach them on some paper towels; sear and canramelize them cut side down in a cast iron pan of a few tablespoons of Bacon Fat, then put them in a 450F oven for around a half hour they would be quite nice and roasty toasty.
probably 15 minutes, at high heat to roast on second thought… it’s all an experiment.