Zucchini and Yellow Squash Gratin

Sorry I don't have any pictures of this! I made it for small group last Friday night and we devoured it before I thought about taking any pics :) It was excellent!! I can't wait to make this dish this summer with zucchini and yellow squash from my garden. I left out the Panko to make it a little bit more low-carb friendly and used regular white onions instead of shallots because that's what I had on hand.
 
Zucchini and Yellow Squash Gratin 
2 tablespoons butter
2 medium zucchini (about 7 ounces each), sliced crosswise 1/4 inch thick
2 medium yellow squash (about 7 ounces each), sliced crosswise 1/4 inch thick
2 shallots, minced
2 garlic cloves, minced
Coarse salt and ground pepper
1/2 cup heavy cream
1 cup panko
1/2 cup grated Parmesan cheese
Preheat oven to 450. In a large skillet, melt butter over medium heat; add zucchini, yellow squash, shallots, and garlic. Season with salt and pepper. Cook, stirring occasionally, until zucchini and squash are crisp-tender, 4 to 6 minutes.

Add cream, and cook until thickened, about 5 minutes. Remove skillet from heat; stir in 1/2 cup panko and cup Parmesan.
Spoon mixture into a shallow 2-quart baking dish. Sprinkle with remaining panko and Parmesan; season with salt and pepper. Bake until top is golden, 8 to 10 minutes.