Apple Muffins

Apple muffins is a new recipe I am trying. I have to say I have adapted the recipe to perfection. The issue is the recipe creator is WAY off on how long these cook for. Because there is apples in there, it makes the muffins dense creating air pockets, releasing juices, which in turn takes longer to cook. The website (linked below) says 350 for 20-24 minutes. These took almost 40 minutes to cook at 350 degrees. Also, there is no rising agent in these muffins. Baking soda does not rise a lot you need baking powder. So, I added that in and upped the cinnamon amount. I do wonder if shredding the apple, like you would zucchini, would make it less dense and cook better. I will try that next time. To be a good baker or cook, you need to learn how to change a recipe, fix a recipe if its wrong. Not just keep going when it clearly is not working time and time again. That recipe below is exactly that. I think you need to shred the apples for the perfect muffin and then cut back to 2 cups not 3 cups.
You Will Need:
2 Cups Sugar
2 Eggs
1 Cup Oil (or melted butter would be better)
1 tbsp Vanilla
3 Cups Flour
3 Cups Diced Apples 
1 tsp Baking Soda
1 tsp Baking Powder
1 tsp Salt
1 tsp Cinnamon
Brown Sugar, for topping

recipe adaption