Impossible Asparagus Pie

2 cups cooked asparagus, cut up
1 cup shredded Cheddar cheese
1/2 cup chopped onions
3/4 cup Bisquick
3 eggs
1 1/2 cups milk
1 teaspoon salt
1/4 teaspoon pepper

Combine first 4 ingredients and place in greased 10-inch pie plate. Blend remaining ingredients and pour over asparagus mixture. Bake at 400 degrees F for 35 to 40 minutes.