Bisquick Impossible Tuna Melt Pie

I have always made this, I got the recipe from the back of the Bisquick Box.

• Ready In: 45 mins
• Serves: 6

Ingredients

• 2  cups onions, chopped
• 1⁄4 cup butter
• 2 (6 1/4ounce) cans tuna, drained and flaked
• 1 3⁄4 cups cheese, shredded
• 3  eggs
• 1 1⁄4 cups milk
• 1  cup Bisquick baking mix
• 1⁄4 teaspoon salt
• 1⁄8 teaspoon pepper

Directions

1. Preheat oven to 400 degrees.
2. Grease baking dish.
3. Cook and stir onions and butter in skillet over low heat until onions are light brown. Sprinkle tuna, 1 cup of the cheese and the onions in baking dish.
4. Beat eggs, milk, baking mix, salt and pepper until well blended.
5. Pour into baking dish.
6. Bake 25 minutes. Top with remaining cheese to within 1 inch from edge. Bake 5 to 8 minutes longer or until knife inserted in center comes out clean. The pie can be done even though some melted cheese adheres to knife.