Preheat the oven to 350°F/180°C Line two baking sheets with parchment paper or spray them lightly with nonstick cooking spray.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
With an electric mixer, beat the butter and sugar on medium speed until light and fluffy, about 2-3 minutes.
Beat in the eggs, one at a time until thoroughly combined. Scrape down the bowl as needed. Beat in vanilla extract.
Stir the dry ingredients into the creamed butter mixture on low speed. Do not overmix. Stir in the oats, candy, and chocolate chips.
Using a cookie scoop, or two spoons, scoop generous 2 Tablespoons of dough and roll the dough into a smooth ball. Place the each cookie on the prepared baking sheets, spaced at least 2 inches apart.
Bake until the cookie edges turn golden brown, about 22 to 25 minutes. If baking more than one cookie sheet, rotate the baking sheets from top to bottom racks in the oven. Let the cookies cool on the baking sheets for 5 minutes. Transfer the cookies with a wide metal spatula to a wire rack.