Preheat oven to 350 degrees. 

Grease a 9x13 pan and set aside. 

In a bowl combine flour, baking soda, and cinnamon. Set aside. 

In a large bowl cream butter and sugar until light and fluffy. This takes 2-3 minutes.

Add eggs and vanilla and mix to combine well.  

Stir in flour mixture and mix just until combined. 

Stir in apples just until combined. 

Spread batter into the greased 9x13 pan. 

Bake for 35-40 minutes or until toothpick inserted into the middle of the cake comes out clean. 

Note: You can eat this cake as is. It is delicious. But I also like to make a simple powdered sugar glaze to drizzle on top. Just mix 1 cup powdered sugar with a couple tablespoons of milk. Whisk to together and add more milk or more powdered sugar until you get the desired texture. You want it so that it drizzles easily. Drizzle over cooled cake.