In the bowl of a standmixer or with a handmixer, cream together the butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the eggs, one at a time, followed by the vanilla extract.
In a separate large bowl, stir together the oats, flour, baking powder, baking soda, salt, cinnamon, and cloves, until combined.
Gradually beat the dry ingredients into the wet until all ingredients are combined into a thick dough.
Beat in the coconut, chocolate chips, and chopped walnuts until just incorporated.
Refrigerate dough for about an hour. (Or freeze for 15-20 minutes.)
Scoop cold cookie dough onto prepared baking sheets, leaving about 2 inches between each cookie. Press the tops down slightly to flatten the cookie.
Bake cookies at 350F for 10-12 minutes, until the edges are golden brown.
Remove cookies from oven and let cool 5 minutes on baking sheet, then transfer to a wire track to cool completely before serving.