Yam Gratin
(bake in 350-degree oven; total baking time about 1&3/4 hours)
1 onion finely sliced and sautéed in olive oil until transparent 2 cups evaporated milk or heavy cream 1 tsp kosher salt or ½ tsp regular salt 3 lbs yams, peeled and sliced ¼” thick 1 ½ cups grated cheese (cheddar, Monterey jack or Swiss, or a combination thereof)
1. Spray large (3-quart) casserole dish with nonstick spray (important; don’t skip this step).
2. Stir together evaporated milk (or heavy cream) and salt in large bowl. Add sliced yams to bowl, coating with milk/cream as you add them; make sure they are all coated.
3. Layer 1/3 of yams slices in baking dish. Sprinkle with half of the cheese. Repeat with another 1/3 of yams and remainder of cheese. Top with remaining yams. Pour any remaining milk/cream over top.
4. Place uncovered casserole on center rack of oven (bottom third of oven works OK if you need to bake something else on the top third) on a baking sheet (very important) to catch boil-overs.
5. Bake 30 min.
6. Remove from oven and press fork or spatula carefully against top layer to allow liquid to flow over “crust”. Replace pan in oven.
7. Bake 30 minutes more. Remove from oven a second time.
8. Press top layer to allow liquid to flow over top a second time, and replace pan in oven.
9. Bake another 40-45 minutes or until yams are tender.
10. Remove from oven and let rest 15 minutes before serving.