Combine the peanut butter, butter and vanilla extract with a mixer until combined. Add 1 cup of the powdered sugar and mix until well combined. Add additional powdered sugar until the mixture is at a consistency where you can create balls that hold their shape. Create about 16 balls, melt the chocolate and dip each peanut butter ball into the chocolate. Set aside to dry and refrigerate.

Preheat oven to 300°F. Whisk together dry ingredients in a large bowl. Mix wet ingredients in another bowl. Combine wet and dry, then add hot water and mix until thinned. Fill cupcake liners halfway and bake for 18-23 minutes. Cool completely.

Beat butter and peanut butter until smooth. Add powdered sugar, vanilla, salt, and milk to reach desired consistency. Pipe onto cooled cupcakes. Refrigerate until frosting is firm.

Make ganache by heating heavy cream, pouring over chocolate chips, and whisking until smooth. Dip the tops of frosted cupcakes into ganache. Top each with a peanut butter buckeye. Chill before serving.