Chicken Tetrazzini without bouillon whites

1/2 cup onions sliced 1/4 cup margarine 1/4 cup flour, all-purpose 1/2 teaspoon salt 1/2 teaspoon sage ground * 1/4 teaspoon black pepper * 2 cups chicken[...]

1 pound chicken cut up 9 ounces pasta, linguine 2 tablespoons olive oil 2 tablespoons butter or margarine 2 cloves garlic minced 2 cups mushrooms sliced 10[...]