Is carrot soufflé supposed to rise like a classic soufflé?
Not dramatically. This is a soufflé-style casserole. It should puff a little and feel airy, but it is meant to be stable and scoopable, not towering and fragile.
Can I make it ahead of time?
Yes. My favorite low-stress move: cook and puree (or mash) the carrots up to 2 days ahead. Store the carrot puree covered in the fridge. When ready, bring it closer to room temp for about 20 minutes, blend with the remaining ingredients, then bake.
You can also bake the whole dish ahead: bake as directed, cool, cover, and refrigerate up to 2 days. Rewarm (covered with foil) at 325°F until hot in the center, about 20 to 30 minutes, then uncover for the last 5 minutes to wake the edges back up.
Why is mine watery?
Usually it is excess moisture from the carrots. Drain them well after boiling, then let them sit in the colander for a minute or two. If you puree while they are still steaming-wet, the soufflé can bake up loose.
Can I reduce the sugar?
Absolutely. You can cut the sugar to 1/4 cup without major texture issues. It will taste more like a savory side, which I personally love with roast chicken or ham.
What size dish should I use?
A 2-quart baking dish (or an 8x8-inch pan) is perfect. Aim to fill the dish about halfway to two-thirds full so there is room for a gentle puff. If you use a larger dish, it will bake faster and be a bit less tall. If you use a smaller dish, budget extra bake time.
How do I know when it is done?
Look for a puffed top, browned edges, and a center that feels set (not sloshy). A knife inserted near the center should come out mostly clean with a moist crumb or two. If you like an objective check, the center should read about 165°F on an instant-read thermometer.