Preheat your oven to 350°F. Line two baking sheets with parchment paper. Set aside.

In the bowl of a stand mixer with the paddle attachment or in a large bowl using an electric hand mixer, beat butter, both sugars, baking powder, baking soda and salt on medium-high speed until light and fluffy, about 2 minutes. Beat in eggs, one at a time, scraping down the sides of the bowl after each addition. Beat in vanilla extract until just combined. Add flour; stir on low speed or with a spatula to combine. Stir in cereal, chocolate chips, chopped chocolate, pretzels and toffee bits until just combined.

Scoop approximate 1/4-cup balls of dough; roll into a ball, then place on parchment paper-lined baking sheets, spaced at least 2 inches apart (you will only be able to fit 6-8 cookies on each baking sheet, so you'll be baking in batches). Press down each dough ball slightly, then top with extra cereal and pretzels, as desired.

Bake for 8 minutes, then briefly remove cookies from the oven and bang the baking sheet on a counter or stovetop. Return the cookies to the oven and bake another 7 to 9 minutes or until the cookies are just set in the centers and golden-brown along the edges. Cool the cookies for 5 minutes on the baking sheets, then transfer to a cooling rack to cool completely.