It may seem like a no-brainer, but there are some best practices for saving pizza in the freezer for later.
Follow these simple steps and your future self will thank you:
1. Let the pizza cool completely.
2. Make sure the slices are fully separated.
3. Portion out the slices for how you'll want them reheated later. i.e. Will you want to reheat half a pizza, or just one slice?
4. Fold the cold pizza slices so the cheese sides are facing each other. If it's just one piece, don't fold it ;-).
5. Wrap each portion in foil or waxed/parchment paper (if it came in a lined box, you could use that paper. The goal is to reduce the amount of air in contact with the pizza).
6. Place the wrapped packet in a resealable bag and date and label it (What kind of pizza is it? This may be important later if you have picky eaters in your house.)
Prepping a pizza for the freezer:
Everyone probably has their own favorite way to reheat a pizza. Maybe it's just thrown in the microwave for 30 seconds? For crispier crust, reheat on a baking sheet in a preheated oven, or stove top on a skillet (pro-tip: cover the skillet to melt the cheese). Some people swear that on the grill is the way to go.
However you do it, we recommend pulling out the portion you plan to eat from the freezer at least 30 minutes before your meal, or even putting it in the fridge the night before to thaw.
Once thawed out, open the foil packet and separate the pieces (if you had a pizza with lots of toppings, you might have to redistribute/rearrange here). You may want to add some new toppings to make it more exciting or use up some other leftovers; olives, sausage, cooked spinach, squash, roasted veggies... all would be great additions to a slice of pizza!
Then, simply reheat in your favorite way. Note that if you put the pizza in the oven, you can reuse the foil it was wrapped in to line a baking sheet, saving you some clean-up later once that yummy cheese starts to melt!