Brown sausage according to package directions; drain, reserving drippings.
Cook onion in drippings till tender.
Combine eggs, cream or milk, 1/2 teaspoon salt, and dash pepper; pour into hot skillet.
Add sausage and chilies.
Cook, stirring gently, till set but glossy.
Spoon egg mixture into taco shells.
Pour taco sauce over each; top with some of the cheese.
Heat in 8x8x2-inch baking pan in 350° oven for 10 minutes.