If you use oil (which is a better choice over butter, since butter burns), and GF spices, not sure where else you might be getting dairy or gluten in your veggies.
I roast brussel sprouts, cauliflower, asparagus, sweet potatoes, winter squash, reg. potatoes, apples, pears, endive, raddichio, fennel, parsnips, broccoli, green beans, eggplant, beet... Of all of those, none of them will be ready in 7 minutes with the possible exception of asparagus, if you have really thin spears.
When you're roasting the first thing that happens is all the moisture has to be evaporated from the veg, and only once that happens does browning start, and you want a fair bit of browning for optimum flavor. If you slice up a whole head of cauliflower (which works better than separating it into florets), spread it out on a sheet pan and stick it in the oven, you'll notice that over the course of 20 minutes, what looked like a huge amount of cauliflower shrinks down to a bowl's worth as the water evaporates. Only once it has shrunk does it start browning, and that's when it's at it's best. One head roasted until brown typically only makes a side dish serving for 2 around here.
The other thing to keep in mind is that you need your pieces of a uniform size, which is why slicing the cauliflower works better than separating it. If you have randomly sized pieces, and pieces that are big on one end and small on the other, they're going to cook very unevenly. For broccoli what that means is I buy a bunch of it, and then cut it into spears so each flower has a pencil width's worth of stem attached. The flowers cook quicker than the stem, so that way it balances out.
As for spices, mostly I like to let the flavor of the vegetable shine through - a little salt and pepper is all that's needed. Parsnips often get dressed with horseradish butter, brussel sprouts sometimes get blue cheese or toasted pecans and a dash of red wine vinegar, broccoli I usually toss in a vinaigrette before cooking to get good flavor coverage. But mostly I leave them unadorned. Although a mix of roasted veggies (roast them separately and then mix) pureed makes a really nice "mash" - like sweet potatoes, squash, apples, pears; or I like fennel and potatoes together.
Roasted veggies also can be incorporated into other dishes - salads mostly around here.