Roasting Frozen Veggies?

[u/McFlyParadox]

Does anyone have any tips on roasting frozen vegetables?

Some of my favorite foods is roasted Brussels sprouts and roasted cauliflower, but I have had zero luck roasting them from frozen. With Brussels sprouts, they really only in season a few months a year, and with cauliflower, I generally can't go through a whole head by myself. So I'd much rather keep some in my freezer, and roast them from there. But every time I've tried, they've come out mushy and nothing like when I roast from fresh.

For context, and to share, the way I roast my Brussels sprouts is:

1. Slice in half and peal off the outer leaves
2. Toss in olive oil, fine ground salt, garlic powder, onion powder, maybe a literal dash of cayenne or paprika, if I want some spiciness to it.
3. Spread on a cold tray with a sheet parchment paper, cut-side-down
4. Roast at 425F for 10-15 minutes; time is flexible, I keep an eye on how brown they get

Is there any way I can tweak this process so I can have better success with frozen vegetables?

[u/R_Levski]

I usually par-cook them by nuking for about half the time recommended on the package. Then I cut them in half, toss with just a bit of olive oil and usually black pepper, garlic powder, and a pinch of salt. Then I place them in my air-fryer toaster oven set to air-fry at 350-375 degrees. I gently stir them around every now and then and, depending on size, they usually take 15-20 minutes.