Preheat oven to 425. Sauté bacon until crisp and remove from pan, reserving dripping in the pan.
Wash leek and brussel sprouts and shred, using medium or large shredding blade of your food processor.
Add 4 tablespoons of butter to bacon drippings and sauté leek, sprouts and thyme until wilted. The thyme leaves will fall off sprigs duting sauté, just remember to remove them when finished Set mix aside.
Peel and shred 2 Idaho potatoes, to obtain 2 cups shredded. Place in a colander for 10-15 minutes to drain water. Squeeze out any remaining moisture using a kitchen towel and place in a mixing bowl.
Add one egg, 1/2 cup matzo meal, 1 tsp salt and 1 tsp pepper. Mix and press into a 8 or 9 inch pie pan and bake at 425 for 25-30 min or until the potatoes get some color. When done, reduce oven temp to 350 and remove from oven to assemble quiche.
Add 1- 1/12 cups of the brussel sprout mixture to pie pan (to accommodate either 8 or 9 inch pan. Sprinkle shredded Irish cheese over sprouts.
Whisk together 4 eggs and 1 cup heavy cream, season with 1 tsp each salt and pepper and pour over all quiche ingredients.
Bake at 350 for 25-35 minutes until the eggs are set.
May be served warm or room temperature, either alone or with a fresh salad of dark leafy greens. Enjoy!