This recipe is pretty simple. Even simpler if you have a mandoline or other slicing machine. The thinner the slices, the faster it will cook and the more attractive the presentation will be. You can, however, pull this off without a specialized piece of equipment. A little bit of time and a sharp knife will net you equally lovely results.
I know it seems like a lot of work. It does take a little time to assemble but you can do this in advance. The day I cooked this, I knew was going to be super busy. So I prepped the whole thing in the morning, covered it in foil and popped it in the fridge. Later in the day, I pulled it out to let the glass dish warm a bit before throwing it into the oven. You could probably even prep this the night before, so long as you really wrapped it tightly and kept it refrigerated!
4-5 peeled potatoes (russets or yukon golds work great here)
2 Tbs butter + more for pan
2-3 Tbs flour
1 1/2 cups milk
1/4 cup shredded parmesan
salt/pepper to taste
1)Melt 2 Tbs butter in the bottom of a medium sauce pan on med/low heat. Add flour until a thick paste (roux) is formed. Cook paste for 1-2 minutes. Add milk all at once and WHISK to remove lumps. Cook, stirring continuously until sauce starts to just thicken slightly-- you will start to feel a resistance against the spoon and the sauce should coat the spoon. Don't over thicken! Remove from heat and set aside.
2) Generously butter bottom and sides of casserole. For a small family dinner, I used a glass 9x9 brownie pan.
3)Thinly (between 1/16 & 1/8th of an inch) slice 1 potato. Arrange slices in a single layer across the bottom of the dish.
6) Repeat slicing, layering & seasoning until you reach about 1/2 -3/4 of an inch from the top -- this ended up being 8 layers for me (4 each of zucchini & potato)
7) Carefully pour prepared white sauce over layers.
8) Sprinkle parmesan cheese over top.