"A deliciously rich casserole chock full of crab, mushrooms and sharp Cheddar cheese. Delicious over puff pastry shells or simple toast points. Imitation crabmeat can be substituted, but there is nothing like the real thing!"
Preheat oven to broil. Place mushroom caps on a baking sheet, and brush with oil. Broil until soft and slightly browned.
Meanwhile, melt butter in a saucepan over medium heat. Stir in flour to make a paste. Whisk in milk; cook, stirring frequently, until hot. In a small bowl, beat egg yolks together, then pour a small amount of the hot milk mixture into the yolks. Whisk this yolk mixture into milk in saucepan. Remove from heat, and stir in 1 1/4 cups cheese.
Preheat oven to 350 degrees F (175 degrees C).
Place mushroom caps, hollow side up, in an 8 inch, round baking dish. Cover with crab, and sprinkle with lemon juice. Pour cheese sauce over mushrooms and crab, and top with remaining 1/4 cup cheese.
Bake in preheated oven for 20 minutes, or until hot and bubbly.