4-4.5 quart (4-4.5l) slow cooker
3/4 cup all-purpose flour
1/3 cup granulated sugar
1tsp baking powder
3 tbsp natural peanut butter
1/3 cup milk
3/4 cup packed brown sugar
1/4 cup cocoa powder
1 cup boiling water
Butter bottom and side of slow cooker; set aside.
In large bowl, whisk flour, granulated sugar and baking powder. In seperate bowl, whisk egg; whisk in peanut butter and milk until smooth. Scrape over flour mixture; stir to combine. Scrape into slow cooker; smooth top.
In heatproof bowl, whisk brown sugar with cocoa powder; whisk in boiling water until smooth. Pour over batter; do not stir.
Cover and cook on high until firm to the touch, about two hours. Remove insert from slow cooker; let cool for 10 minutes before serving.
In large bowl, whisk together flour, granulated sugar and baking powder. Whisk together milk, egg and peanut butter; stir into flour mixture. Scrape into greased 8-inch (2 L) square glass baking dish.
In heatproof bowl, whisk brown sugar with cocoa powder; whisk in boiling water until smooth. Pour over cake; do not stir. Bake in 350°F (180°C) oven until cake is firm to touch, about 30 minutes. Let cool for 10 minutes.