Preheat oven to 325°. Line the cupcake pan with paper liners.

In a small bowl, whisk together flour, baking powder, baking soda and salt; set aside.

In a liquid measuring cup combine milk and vanilla; set aside.

In the bowl of an electric mixer fitted with the paddle attachment, place peanut butter, butter, granulated sugar and brown sugar. Beat on medium speed for 3 minutes.

Add eggs to the creamed mixture, one at a time, beating well after each addition and making sure to scrape sides and bottom of bowl.

Add flour mixture and milk with vanilla in three parts beginning and ending with the flour mixture, blending just until combined after each addition.

Scrape down the sides and bottom of the mixer bowl.

Bake 22-25 minutes or until cake tester comes out clean and cupcakes start to pull away from the sides of the pan.

Remove from the oven and cool in the pan for 20 minutes. Remove from the pans and cool completely.

Using the blunt end of a wooden spoon, punch a hole into the center of each cupcake. Place jelly in a piping bag or small plastic bag with the end snipped off. Squeeze about 1 tbsp. of jelly into the center of each cupcake. Ice generously with buttercream frosting.

In the bowl of an electric mixer fitted with a paddle attachment, beat peanut butter and butter until light and fluffy and butter is completely incorporated (no lumps). Do not overmix.

In a liquid measuring cup, combine milk and vanilla; set aside.

Add half of the confectioner’s sugar and half of the milk-vanilla mixture and beat on low speed until just incorporated.

Scrape the sides and bottom of the bowl.

Add the remaining confectioner’s sugar and milk-vanilla mixture and beat on low speed until just incorporated.

Scrape the sides and bottom of the bowl. Icing should be smooth and creamy—do not over mix.