Creamy Brussel Sprout Gratin

1 lb. fresh brussels sprouts- cut in 1/4s
2 Tbsp. canola oil
2 cups onions-sliced thinly
3 Tbsp. all purpose flour
1 1/2 cups milk
1 1/2 cups panko bread crumbs or substitute any type
3 Tbsp. dry porcini mushroom powder-grind in coffee grinder
4 Tbsp. extra virgin olive oil
To taste salt, black pepper and onion powder

Bring a large pot of water to a boil. Cook the sprouts in 3 separate batches until just barely tender in the boiling water. Stop the cooking of the sprouts by immersing in ice water. Drain the sprouts well and pat dry.

Prepare the sauce by heating a sauté pan on medium-high heat. Add the canola oil and the onions. Cook stirring for about 2 minutes.

Stir in the flour, cook for about 1 minute. Add the milk in 3 stages, stirring smooth to avoid the flour from lumping up. Bring to a boil to allow the sauce to thicken. Season the sauce with salt and pepper. Add the cooked brussels sprouts and stir to evenly coat with the sauce.

Place the sprout and sauce mixture in a greased 9x9 casserole dish, spread out to an even layer.

Prepare the topping by combining the bread crumbs, mushroom powder and melted butter. Season to taste with salt, black pepper and onion powder. Mix thoroughly to coat all the bread crumbs with the butter.

Place the crumbs evenly over the brussels sprout mixture. The casserole can be wrapped and refrigerated until the day needed.