Yellow Squash, Zucchini, and Tomato Gratin

This year on Amazon Prime Day I bought a mandolin; not the musical instrument, but the thing that cuts food into evenly-sized slices.  It was on sale for something like only $11, which meant that I basically needed to get it.  And once I have a new kitchen gadget, I obviously have to use it.  

Since the season for all three main ingredients is upon us, I decided to try a version of this.  Yeah, it looks all fancy, and it would be a great side-dish for company.  But when I made it, I ate it as a main part of my meal and I had some pretty yummy leftovers for other lunches and dinners. It doesn't have to be fussy and the mandolin made my slices quickly, easily, and uniformly!  

In fact, the mandolin worked so well, that I'm psyched to try it with apples for fancy pies/tarts this Fall.    

Ingredients:

• 2 onions, sliced
• sliced mushrooms (1/2 or more of a package)
• 1 medium green pepper (optional)
• 4 cloves garlic minced or 2+ tsp already-minced garlic
• 2 zucchini, cut into slices
• 2 summer squash, cut into slices
• 4+ small tomatoes, cut into ¼" slices
• salt
• fresh ground black pepper
• Italian seasoning
• 2.5+ ounces goat cheese, crumbled (I used an herbed chevre from Trader Joe's)
• grated Parmesan cheese
• Panko breadcrumbs
• 3 tablespoons extra virgin olive oil (I actually used a rosemary-infused olive oil, because that's what I had.)

Directions:

1. Preheat oven to 375 degrees. 
2. Spray bottom of 13x9x2 inch casserole dish with nonstick spray
3. Heat large skillet. Add onions and peppers, and saute.  After a few minutes, add mushrooms and cook until onions are translucent and peppers are soft
    
4. Add garlic and saute another minute
   
5. Transfer onion/mushroom/pepper/garlic mixture to casserole dish and spread to cover the bottom of the dish. 
6. Slice other veggies.
   
7. On top of bottom veggies, layer in zucchini, summer squash and tomato.  The original recipe called for one slice of each, but that is pretty darned fussy.  Go with a few and make it uneven. It'll still look great and it'll taste fine!  
8. Drizzle olive oil on top and season with salt, ground black pepper, and Italian seasoning.
     
9. Cover dish with foil and bake for 40 minutes
10. Uncover dish, sprinkle goat cheese, Panko crumbs, and Parmesan cheese on top and continue baking, for another 30-35 minutes, until browned.
       
11.      Serve warm