Peanut Butter Chocolate Chip Cake

2 ounces unsalted butter

1 cup all purpose flour

1/4 tsp baking soda

1/4 tsp baking powder

1/4 tsp salt

1/2 cup tightly packed brown sugar

3 ounces creamy peanut butter

1 large egg

1 egg yolk

1/4 cup sour cream

1/4 cup hot water

1/2 tsp pure vanilla extract

1/2 cup semi sweet chocolate chips