Preheat oven to 375°. Line a baking sheet with parchment paper and set aside.
In a medium-size bowl, whisk the flour, cocoa powder, baking soda, and corn starch together, set aside.
Beat the melted butter and sugars together until smooth. Add the eggs, egg yolk and vanilla and mix until completely combined. Mix in the peanut butter. Pour in the flour mixture and mix until just incorporated. Dough will be very thick. Fold in the rolos and peanut butter chip by hand with a spoon or rubber spatula until evenly distributed.
Scoop 1 rounded tablespoon of dough for each cookie, roll into a ball and place on prepared baking sheet. Flatten them down to the shape you want because they barely spread or rise. Optional - you can add some extra chopped rolos and peanut butter chips to the tops of cookies for presentation.
Place cookies into preheated oven and bake for 7-8 minutes. They may seem underdone but will firm up as they cool. This is what makes them chewy. Remove from oven, let cool on baking sheets for 5-10 minutes before transferring to wire rack to finish cooling.