Cornbread Recipe-Jiffy Copycat

I am not buying premade mixes for baking. Here is an example of what I am using instead:

Jiffy Corn Muffin Mix (copycat)

Makes 8.5 oz=1 box of storebought mix

2/3 cup all-purpose flour
1/2 cup yellow cornmeal
3 tablespoons granulated sugar
1 tablespoon baking powder
1/4 teaspoon salt
2 tablespoons vegetable oil

to make muffins add:
1 egg
1/3 cup milk

1. Combine first 5 ingredients in a bowl, mix well.
2. Whisk in vegetable oil and mix until dry mixture is smooth and there are no lumps.
(If another recipe calls for a box of Jiffy corn muffin mix, add the ingredients above.)
3. To make corn muffins, preheat oven to 400F, spray muffin pan with non-stick cooking spray.
4. Combine mix with egg and milk, mixing well.
5. Fill muffin pan 1/2 full, bake for 15-20 minutes.