Preheat oven to 375 degrees Fahrenheit. 

Choose firm, crisp apple varieties, such as Cortland, MacIntosh, or Honey Crisp. I prefer Cortland or Winesap.

Peel and core apples. While you can use a a sharp paring knife, it is much quicker with an all-in-one apple peeler-corer.

Place apples in an 8 x 8 or 9 x 9 pan and sprinkle with the lemon juice and water. 

Mix dry ingredients (brown sugar, flour, oatmeal, and cinnamon together in a small bowl. Add softened butter, mixing until the ingredients are crumbly.

Sprinkle mixture over apples. 

Bake at 375 degrees for 45 minutes. The apples should be tender when done.

Enjoy!  

For even more deliciousness, pair the warm apple crisp with vanilla ice cream.