Whether you can't eat Jiffy corn muffin mix, or you just don't have any on hand, you can use a variety of substitutions in its place depending on your needs. Replacing the Jiffy mix in your recipe may not be a one-to-one trade, however, so take note of the ingredients you use in the replacement.
Boxed Mix Substitutes
In most cases, you can substitute another corn muffin mix for Jiffy if you prefer. If you are gluten intolerant, for example, you could use Bob's Red Mill Gluten Free Cornbread mix. Those who don't eat dairy can use 365 Organic's Cornbread and Muffin Mix (available at Whole Foods stores). You also can substitute a combination of regular baking mix and cornmeal for Jiffy. Combine 2/3 cup baking mix such as Bisquik baking mix, 1/2 cup cornmeal and 3 tbsp white sugar.
Corn Muffin Mix from Scratch
Making a corn muffin mix from scratch allows you to control the ingredients and make alterations for different dietary needs. To make the equivalent of one 241gr. box of Jiffy mix, combine 2/3 cup flour, 1/2 cup cornmeal, 3 tbsp sugar, 1 tbsp baking powder, 1/4 tsp salt and 2 tbsp oil in a large bowl and stir or whisk until incorporated. You can substitute the flour of your choice, whether it's a whole wheat or a gluten-free option such as rice, soy or potato. This also allows you to control the type of fat used, subbing in a healthier olive oil for lard, for example.
Altering Your Recipes
The type of substitute you use will alter which other ingredients you need to add to your recipe. If you are using a boxed mix that includes milk and eggs -- the type of mix that says "just add water" on it -- do not add those ingredients again. For example, if your recipe calls for 1 egg and 1 cup milk and you were using a "just add water" mix, you would substitute 1 cup water for the other wet ingredient. Add the other ingredients, such as broccoli, cheese or jalapeños, as normal.
Making Corn Muffins
The most basic use for a Jiffy mix substitute is to make corn muffins, which you can do by following the recipe on the Jiffy box. Mix the substitute recipe with 1 egg and 1/3 cup milk. Pour the batter into a muffin tin, filling cups half full, and bake at 204 degrees Cor 15 to 20 minutes. The recipe makes six regular-sized muffins. You can use an egg substitute and non-dairy milk for a vegan version.