Don't be tempted to jam all the cauliflower onto one sheet pan in order to make fewer dirty dishes. Spreading it out on two pans ensures that it gets golden brown.
Preheat oven to 400 degrees F.
Toss cauliflower, shallots, oil, salt and pepper in a large bowl. Divide between 2 large rimmed baking sheets. Roast, stirring once halfway, until starting to brown, about 20 minutes.
Add banana peppers and toss to combine. Continue to roast, stirring once, until the cauliflower is tender and browned, 15 to 20 minutes more. Serve topped with mint and pine nuts.