Calzones are one of my favorite things to make when I want something that can be made in a large batch and then frozen for later use. The batch I made today are not only vegetarian but also meet the requirements to be called VEGAN, no animal products at all. This recipe uses my regular pizza dough recipe and a filling made with a lot of vegetables held together with a creamy white sauce. No cream, no cheese, no eggs. This recipe will make 12 calzones.

Start the pizza dough which rises very fast due to using rapid rise yeast, and while it is rising, make the filling--

2 cup very warm water/hot to the touch
2 Tbl. rapid rise yeast
4 tsp. salt
1 Tbl. sugar
6 Tbl. olive oil
5 to 6 c. all purpose flour

You could also buy already made dough, but with homemade you can control the ingredients.

3 Tbl olive oil
2 medium zucchini, cut into chunks
1 large onion, diced
10 mushrooms, sliced
3/4 cup chopped red or yellow pepper
1 cup cherry tomatoes
3 cloves garlic
4 oz fresh baby spinach leaves
3 Tbl olive oil
3 Tbl flour
1-1/2 to 2s c almond milk
salt and pepper to taste

Put very warm water in a large bowl. Add yeast, sugar, salt and stir until well dissolved. Let stand for a couple of minutes to let yeast start to foam.  Stir in olive oil, add 2 cup of the flour, stir to mix well. Add another 2 cups of flour, mixing thoroughly. Stir in the remaining flour a little at a time, until the dough stops being sticky and can be kneaded easily. Do not put too much flour in, you can always add more.

Once the dough is well mixed, and elastic, knead for about 5 minutes, or until you start seeing bubbles form under the surface of the dough. Place in an oiled bowl, rolling dough around until entire ball of dough has been oiled. Let rest in bottom of bowl, and cover with either cloth or plastic wrap. Let rise for 30 minutes, or until doubled in size. At this point, make the vegetable filling.

Saute whatever vegetables you like, keep the pieces medium size so they don't totally cool down,
and small enough to be easy to eat in a calzone

The spinach only needs to wilt, so add that in at the end.
You may want to pierce the tomatoes so they add to the moisture in the filling
Saute the first 5 vegetables and garlic in 3 Tbl olive oil until they are tender, then stir in spinach and cook until the spinach is wilted, stirring often. Season to taste with salt and pepper or any herbs you like. Set aside.

In a small saucepan, heat the 2 Tbl of olive oil and stir in the flour, whisking it until it gets smooth. Let it bubble for a minute or two, this cooks the flour a little and improves the flavor. Then pour in the almond milk. I have to admit, the amount is an estimate. Let the almond milk heat up, whisking the mixture to fully blend in the roux (flour and oil mixture). 

You could use any milk substitute here, or even vegetable broth as the liquid.

You can see the thickness of the sauce before stirring into the filling. 
You want it to be thick, so start with a lesser amount of liquid and add more as you go. you want the final sauce to be about the thickness of thick pancake batter, if that makes sense, because the juices with the vegetables will thin it out a bit. 
Let the filling cool a little before assembling the calzones.
In fact, you could make the filling first if you are not trying to save time.
Add the sauce into the vegetables and stir to completely mix. taste and add seasonings to taste. Set aside to cool.

Preheat oven to 375 degrees F. Lightly grease a large baking pan or cookie sheet and sprinkle with a little bread crumb or corn flour. (Check your breadcrumb ingredients to make sure it is vegan.)

The dough should be ready to use after 30 minutes. Punch down dough and place on the counter. covered with an upside down bowl to rest for ten minutes.

Divide into 12 evenly sized pieces. On a slightly floured surface, roll out a ball of dough, one at a time.  Roll until very thin and about 4 or 5"  in diameter. Place one quarter cup of the vegetables onto on center of the dough. Fold over the dough  and pinch together the edge by folding it onto the edge on top or by folding it over onto the top side and pressing with a fork. You want to make sure you have a tight seal so you don't get any sauce running out.

Notice how the sauce and the vegetables hold together, you don't want a runny filling,
it will get looser when it heats in the oven.

Leave some space around the calzones.
They do not need to be filled too much, if they aren't, they don't split while cooking.
Place on prepared pans, and repeat with other calzones. Place so they are not touching each other, so that as they rise, they will not touch. Cover with a cloth and let rise for another 15 minutes.

Bake for about 16 to 18 minutes, or until the tops are browned nicely. Remove from oven and cool on a rack. You can serve these with heated tomato sauce or eat as is. 

If you want to freeze these, lay them on the pan and put into the freezer until firmed up, and place in a plastic freezer bag. Reheat for about 15 minutes in a preheated 400 degree oven.