Melt chocolate and let it cool slightly.
Whisk flour, cocoa powder, espresso powder, baking powder, and salt.
Beat butter and sugars until creamy.
Add eggs and vanilla; mix well.
Mix in melted chocolate.
Combine dry ingredients with wet mixture.
Chill dough for 1 hour.
Shape the Cookies
Preheat oven to 350°F (177°C).
Scoop dough and flatten slightly.
Place frozen peanut butter ball in center.
Cover and roll into a smooth ball.
Place on baking sheet with space between each.
Bake
Bake Peanut Butter Filled Brownie Cookies for 12–13 minutes.
Cool on baking sheet before transferring to rack.