dish, whisk the hot water into the cocoa powder. in another bowl, whisk together the flour, baking powder, baking soda, and salt. set aside.
in a medium saucepan, melt together the butter and sugar over medium heat until fully smooth. transfer to the bowl of a stand mixer and beat on low speed until the mixture is cooled. add in eggs one at a time, beating until fully combined. stir in the vanilla and cocoa/water mixture. gradually add in the remaining dry ingredients alternating with the sour cream- beginning and ending with the dry ingredients.
fill cupcake liners 2/3 full with cupcake batter. push one of the peanut butter cups into the 