Hot Chicken Meatball Sandwiches with Marinara, Mushrooms and Cheese

Remember those Cheese Stuffed Chicken Meatballs I posted about earlier this year?
I've made them a couple of times since then, and most recently I used them to make these hearty meatball sandwiches. 
I had some of the chicken meatballs in the freezer  so I just thawed them and warmed them up before assembling the sandwich.
If you saute the sliced mushrooms, warm the marinara and meatballs and keep everything warm while preparing the rolls, the sandwich assembly takes only minutes.
These require a sturdy rolls, a split and sliced baguette, or bolillo rolls. I used Telera rolls from the store (similar to bolillos, but a bit softer.)
It's best if you toast the cut side of the rolls under the broiler element of the oven until golden brown. After lightly toasting, I spread cut side of the rolls  with garlic butter and popped them under the broiler for another few seconds, then placed the cheese on the roll, and placed  under the broiler again until the cheese just began to melt.)  I used provolone cheese, but anything goes ~ your choice. If you like peppers ~hot or mild, by all means, add some.
I find the sandwiches are easier to manage if you cut each meatball in half (no rolling off of the bun.)
Just layer the rest of the ingredients any way you wish and enjoy. I serve them with a sharp knife and fork for easier eating ~ but if you're brave you might prefer eating them as you would a traditional sandwich, and with napkins!
Since it's summer and basil is growing, I tucked in a few leaves. If you don't care for it, or it's not in season just omit.
Thank you for coming by today I hope you're having a great week!
Bon appétit !
~mari