Place 2 cups of the oats in a food processor and grind until it has a flour-like consistency. Place the ground oats in a large mixing bowl.
Roughly chop the apples, removing the seeds and core. Grind in the food processor until it begins to resemble apple sauce. You may need to scrape down the sides. Some chunks are okay. Scoop the apple mixture into the mixing bowl.
To the mixing bowl, add the remaining 1 cup of whole oats, kale, and honey. Mix to combine. Add additional oats or kale if the mixture is too wet, and honey or water if it is too dry.
Preheat oven to 350F. Lightly flour your surface as the mixture will be sticky. Roll out the dough to approximately 1/4" thick. Using your desired cookie cutter, cut out the treat shapes and place them on a sil pad or parchment paper lined baking sheet.
Bake treats at 350F for 15 minutes. Turn off the oven, leaving the cookies inside, and let them sit for two hours. This will make the cookies crunchier. For soft cookies, remove them after the 15 minutes to cool at room temperature.
Store soft treats in an airtight container, kept in the refrigerator, for up to 2 weeks. Hard treats can be kept at room temperature up to 3 weeks.