1 slow cooker liner
1 cup brown sugar
2 eggs
2 teaspoons vanilla extract
½ cup butter, softened or melted
2 cups cake flour
2 teaspoons baking powder
1 teaspoon baking soda
¼ teaspoon salt
¾ cup peanut butter
¾ cup buttermilk
2 cups semisweet chocolate chips
Put a slow cooker liner in a 6-quart slow cooker.
Place chocolate chips in a large microwave-safe bowl. Melt in microwave for 25 seconds at a time, mixing after every 25 seconds. Continue cooking and mixing until chocolate is completely melted.
In a large bowl, use an electric mixer (or whisk if you don't have a mixer) to blend sugar and eggs until thick, fluffy and pale in color.
Add vanilla extract and butter. Mix until fully incorporated.
In a bowl, mix together cake flour, baking powder, baking soda and salt.
Add half of the flour mixture into the egg mixture. Mix until well combined. Add the remaining flour and mix again.
Add peanut butter and buttermilk. Mix until everything is fully incorporated.
Evenly spread half of the batter into slow cooker.
Spread half the melted chocolate on top, leaving about 1 inch of the batter around the slow cooker exposed (like a pizza crust).
Evenly spread a quarter of the batter over entire top.
Spread the rest of the melted chocolate on top, leaving about 1 inch of the batter around the slow cooker exposed.
Use the last quarter of batter to cover entire top layer.
Line the top of the slow cooker with a few paper towels to absorb any excess moisture.
Cover and cook on high for 2 hours, 15 minutes.
Remove cake from slow cooker by lifting liner up and out of the slow cooker pot.
Serve as is or with ice cream or whipped cream.