Preheat the oven to 350°F. Line two baking sheets with parchment paper or silicone baking mats.

In a large bowl, using a hand mixer, cream together the butter, granulated sugar, and brown sugar. Add the eggs and vanilla and mix until just combined.

In a large bowl, whisk together the flour, salt, baking soda, and baking powder. Place the oats in a blender and grind until fine. It’s okay to have some chunks. Whisk the oats into the flour mixture and then slowly stir the flour mixture into the sugar mixture.

Place the frozen chocolate bar in the blender of food processor, and pulse about 5 to 10 times to grind it. Stir the chocolate flakes, chocolate chips, and chocolate candies into the dough. If desire, add the walnuts and stir until just combined.

Using a medium cookie scoop (about 2 to 3 tablespoons), scoop the cookie dough portions onto the prepared baking sheet at least 1 inch apart.

Bake for 8 to 11 minutes, or until the edges are lightly golden brown. They should look a little doughy in the middle. Let the cookies cool on the baking sheets for a few minutes and then transfer to a wire rack. Store in an airtight container at room temperature for up to 3 days.