Preheat the oven to 350. Line a baking sheet with parchment paper, or grease it with butter.
In a large bowl, combine the oats, flour, baking powder, baking soda, salt and cinnamon.
In a small bowl beat together the butter and sugar until it is fluffy and creamy. Add the eggs, vanilla and milk, and beat until it just comes together.
Make a pit in the dry ingredients and pour the wet ingredients into the center. Using a spatula, fold the cookie dough together until it is thoroughly mixed (no puffs of dry flour).
Mix in the peanuts, raisins and chocolate chips.
Pinch off about 2 tablespoons of cookie dough and roll it into a ball. Place it on the baking sheet, and repeat with the remaining dough, spacing the cookies about 1 inch apart. Use a fork to flatten the cookies.
Bake for about 24 minutes, flipping the tray around halfway through. When the cookies become toasted brown, remove them from the oven and transfer to a wire rack to cool.
Store in an airtight container for up to 1 week.
Note: You can store the cookie dough in the freezer for up to 3 months, and when you’re ready to make another batch you can start from step 6 after removing the dough!