I put this together one night for dinner and it has become a family favorite; it's fast, easy and my version of a panini sandwich. I make it without meat, but you could add meat if you wanted.
1 loaf french bread (Target's is my favorite)
sliced provolone cheese
First, saute the mushrooms in garlic and butter. Then, slice the bread in half lengthwise and crosswise (so you have 2 HUGE sandwiches). Build the sandwich with the cheese, spinach and mushrooms and then grill each sandwich half. Slice and serve.
I grill it on large griddle. You could grill individual sandwiches, if you prefer.
This just gets you started...there are many possibilities!