Preheat oven to 350 degrees. In a mixer cream together both sugars, butter, salt, and cinnamon on medium low setting. Incorporate eggs scraping sides as necessary. Create corn starch slurry by wisking cold water and cornstarch together. Incorporate this to the wet mixture. Add oats and apples. Mix thoroughly. Let sit for 20 mins to let oats soak in some of the moisture. On a nonstick cookie sheet drop 12-2 ounce balls of dough roughly 3 inches apart. Flatten dough half way down with spatula. Make a thumbprint in the center of each ball of dough. Place in oven 13-17 minutes rotating pan half way through. Cookies are ready when oats are golden brown around the edges. Let cool on cooling rack.