Baked Leek and Sweet Potato Gratin

1 1/2 tablespoons grapeseed oil, divided
3 medium leeks, white and light green parts chopped (6 cups)
3 cloves garlic, minced
3 tablespoons chopped fresh rosemary, divided
2 medium sweet potatoes, peeled and cut into 1/8 inch thick slices
1/3 cup vegetable broth
3 tablespoons italian seasoned dry breadcrumbs *


Preheat oven to 450.  Coat a 10-inch round casserole dish with coconut oil.
Heat 1 tablespoon grapeseed oil in nonstick skillet over medium-high heat.  Add leeks, garlic, and 1 1/2 tablespoons rosemary.  Saute 8 minutes or until softened.  Season with salt and pepper if desired.
Arrange one-third of the sweet potato slices over the bottom of the casserole dish, overlapping slightly.  Spread half of the leek mixture on top.  Arrange another one-third sweet potato slices over leeks.  Top with remaining leeks followed by remaining sweet potatoes.  Drizzle broth over the top.  Cover the pan with foil and bake for 35 minutes.
Stir together breadcrumbs, remaining 1 1/2 teaspoons of oil, and remaining 1 1/2 tablespoons rosemary in a small bowl.  Remove the foil from the gratin and sprinkle with breadcrumb mixture.
Bake, uncovered, for 15 minutes or until breadcrumbs are browned and crisp.  Let gratin cool slightly before cutting into wedges and serving.
* Store-bought breadcrumbs containt a surprising amount of unpronouncable ingredients (i.e., preservatives).  Homemade breadcrumbs are really simple to make, so I highly recommend you make your own.  If you don't have homemade bread, buy whole grain bread.  (I like Ezekial bread).  Leave a few pieces out overnight so they get stale.  Put them in your food processor and process until they are crumbs.  These breadcrumbs will last for a long time in the freezer.  For this particular recipe, I added italian seasoning to the food processor.