Zucchini Au Gratin Stacks

 By DELISH these were actually pretty easy to make and delicious!

• Cooking spray 

• 2 

  large zucchini, sliced into 1/8" coins, divided

• Kosher salt

• 3 

  cloves garlic, grated or finely chopped

• 1/2 c. 

  whole milk 

• 1 Tbsp. 

  chopped fresh thyme or 1 tsp. dried thyme

• 1 Tbsp. 

  Dijon mustard

• 1/2 tsp. 

  freshly ground black pepper 

• 1 1/2 oz. 

  Parmesan, shredded (about 1/2 c.), divided

• 1 1/2 oz. 

  Gruyère, shredded (about 1/2 c.), divided

• 1/3 c. 

  panko bread crumbs 

• 1 Tbsp. 

  extra-virgin olive oil 

• Marinara sauce, for serving 

• 1. Step 1Preheat oven to 425°. Spray a standard 12-cup muffin tin with cooking spray. Arrange one-third of zucchini on a paper towel-lined baking sheet; season with a pinch of salt. Repeat with remaining zucchini, separating each layer with paper towels. Let sit 10 minutes.
  2. Step 2Meanwhile, in a large bowl, whisk garlic, milk, thyme, mustard, and pepper. Stir in half of Parmesan and half of Gruyère. Add zucchini and toss to coat.
  3. Step 3Layer zucchini slices in prepared muffin cups, evenly dividing slices among cups. Pour remaining cheese mixture in bowl over stacks. Bake 20 minutes.
  4. Step 4Meanwhile, in a small bowl, combine bread crumbs, oil, and remaining Parmesan and Gruyère. Top zucchini stacks with bread crumb mixture. Continue to bake until topping is golden brown and crispy, 20 to 25 minutes. Let cool 5 minutes before serving.