Creating your Apple Cinnamon Sheet Cake is easier than you might think. Follow these clear steps for a successful bake:

1. Preheat your oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan.
2. Mix Dry Ingredients: In a large bowl, combine the flour, sugar, baking powder, cinnamon, and salt. Mix well to ensure all ingredients are evenly distributed.
3. Combine Wet Ingredients: In another bowl, whisk together the melted butter, eggs, milk, and vanilla extract until smooth.
4. Mix Together: Pour the wet mixture into the dry ingredients and stir until just combined. Be careful not to over-mix; a few lumps are okay.
5. Fold in Apples: Gently fold in the diced apples and walnuts or pecans (if using) until evenly distributed in the batter.
6. Pour Batter: Spread the batter evenly into the prepared baking pan.
7. Bake: Place in the preheated oven and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool: Once baked, remove from the oven. Allow the cake to cool in the pan for about 15-20 minutes before transferring to a wire rack to cool completely.
9. Serve: If desired, dust with powdered sugar for an extra touch before slicing.

Following these steps will guide you in creating a wonderfully moist and delicious Apple Cinnamon Sheet Cake that everyone will adore.