Preheat oven to 350° F.
Whisk together flour, baking powder, baking soda, and salt in a bowl until evenly combined.
Combine butter, brown sugar, and granulated sugar in a large bowl and beat with an electric mixer on medium high speed until light and fluffy, about 3 minutes. Beat in vanilla, then add the eggs 1 at a time, beating well after each addition.
Add the flour mixture and beat on low until the dough just comes together.
Add the chocolate candies, oats, pretzels, and white chocolate chips and stir with a large spoon until evenly mixed.
Scoop cookie dough and form 1 inch balls and space cookies evenly apart on a baking sheet. Press the dough balls into thick disks with the palm of your hand.
Bake 10-12 minutes until the cookies are golden brown at the edges and barely brown in the middle. Rotate the baking sheet(s) front to back halfway through.
Cool the cookies on the baking sheets for 1 minute, then transfer them to a wire rack to cool completely.