1½ cups flour
1½ cups milk (substitute water if you’d like them to be pareve)
1 tablespoon sugar
I teaspoon vanilla
Beat eggs with sugar, oil and vanilla in a large bowl. Stir in flour until no lumps are visible. Add milk and mix until well combined.
Brush an 8 or 9 inch skillet or crepe pan lightly with oil. Heat over medium high flame. When the pan is hot, pour in approximately 1/4 cup batter and cook about one minute or until crepe is golden on the bottom. Flip the crepe and cook 45 seconds to brown the other side. Remove and cool on a rack or paper towel. Stack the blintzes only after they have cooled somewhat. Unfilled blintzes freeze well. Defrost in the refrigerator.
for the cheese sauce and fillings:
2 3/4 cups milk
1 stick butter plus more for the baking dish
5 tablespoons flour
1 teaspoon kosher salt
1/8 freshly ground pepper
1/8 teaspoon nutmeg
3 ounces grated Swiss or Emmenthaler cheese
32 ounces frozen spinach
1 small onion, minced
1 cup cottage cheese
1 cup fresh mushrooms, chopped
prepare the cheese sauce
Bring milk to boil in a small saucepan. Melt butter in a large saucepot over medium heat. Add flour and stir to combine, cooking for 2 minutes. Remove from heat and slowly add milk, stirring constantly. Return to heat and bring to a boil once more. Reduce heat to low and season with 1/2 teaspoon salt, pepper and nutmeg. Cook until sauce is thick enough to coat the back of a spoon.
Remove from heat and stir in 1 cup of the grated cheese. Cover the surface with plastic wrap to avoid a film and set aside.
prepare spinach filling.
Defrost spinach and drain as much liquid as possible. Heat 2 tablespoons butter in a large skillet. Add half the minced onion. Cook 2 minutes or until translucent. Add spinach, season lightly with salt and pepper, and sauté until most of the moisture has evaporated. Add 1 cup of cheese sauce. Cook five minutes over low heat. Remove from heat and set aside.
prepare mushroom filling
Combine cottage cheese and egg and remaining salt. Heat 2 tablespoons butter in a skillet, add remaining onions and sauté 2 minutes, or until translucent. Add mushrooms and continue to sauté until soft and excess moisture has cooked away.
Remove from heat; add cottage cheese mixture and 1 cup cheese sauce. Combine well.
assemble the gateau:
Butter a 9” round baking dish. Place 1 crepe in dish. Spread with 2 tablespoons spinach mixture. Top with a crepe. Spread with 2 tablespoons of mushroom mixture. Top with another crepe. Continue alternating crepes with layers of spinach and mushroom fillings, ending with a crepe. (Up until this point, the gateau may be prepared in advance.)
Heat oven to 350°. Spread top and sides of gateau with remaining cheese sauce and sprinkle with remaining grated Swiss cheese. Bake 30 to 40 minutes or until cheese is lightly browned. Serve hot, sliced in wedges.