Preheat oven to 375°F.
In a large bowl, with an electric mixer, cream butter, sugar, and brown sugar on medium-high speed until light and fluffy, about 3 minutes. Scrape down the bowl 2 to 3 times during this time.
Add peanut butter and mix to incorporate. Then beat in eggs and vanilla.
In a medium bowl, whisk together flour, baking soda, cinnamon, and salt. Add dry ingredients to the peanut butter mixture and mix until fully incorporated.
Now fold in the grated and diced apple, just until evenly incorporated.
Drop about 2 tablespoons of dough onto an ungreased baking sheet, about 2" apart. I like to use a medium scoop (mine is 1⅝" diameter), loaded just a bit generously.
Bake for 12 to 14 minutes, or until golden brown. Let cool on baking sheet for 2 minutes before removing to wire racks to cool completely.