I honestly wish I had an appetite pushing me towards caloric surplus. I have difficulty intaking anything about maintenance calories, so I stay skinny. If I COULD eat a surplus, I would just hit the weights more than I currently do. Compound lifts every day. Throw in some strongman exercises. Being able to eat enough to get fat is a super power, people just don't know where to channel it.
This also requires virtually no change in diet, except ensuring you're reaching your protein goals every day.
Four Burger King Regular Chocolate Shakes will put you above maintenance almost certainly. If you don't want to GOMAD or anything and just want calories, just go do that. You can do it in four eating cycles if you don't have allergies / intolerance. Don't know that pure caloric surplus is worthwhile but there you have it.
This also requires virtually no change in diet, except ensuring you're reaching your protein goals every day.