Heat oven to 400°. Grease pie plate, 10”x 1 ½ “.
Heat beans in 1 inch salted water to boiling.
Cook uncovered 5 minutes.
Cover and cook until tender, 5 – 10 minutes, drain.
Mix beans, mushrooms, onion, garlic and cheese in plate.
Beat remaining ingredients until smooth, 15 seconds in blender on high.
Pour into plate.
Bake until knife inserted between center and edge comes out clean, 30 – 35 minutes.
Cool 5 minutes.