Yield 12 cupcakes
Preheat oven to 350 degrees (F) after positioning the rack in center of oven.
Grease a 12-cup muffin tin or line with papers.
In a medium-bowl, combine gluten-free flour, xanthan gum (if it is not already in your flour blend), salt, and baking powder. Set aside.
In another medium bowl combine oil, sugar, and vanilla. Add eggs and beat with an electric mixer at medium speed for one minute until fluffy.
Add the flour mixture to the egg mixture and combine until it starts to come together. Then add the milk. Combine thoroughly.
Spoon batter evenly into paper liners or a greased muffin tin.
Bake for 18 - 22 minutes or until a toothpick inserted in the center comes out clean.
Let cakes cool for 15 minutes on the counter, then remove to a storage container with a lid resting on the top--but not snapped tight to let cool completely. This will keep them moist.
*See notes below
In a microwave-proof glass bowl (or over a double boiler), melt together 1 stick of butter, 1/2 cup smooth peanut butter, 16 ounces confectioners' sugar, and 1 teaspoon salt. Stir to combine. Heat for another minute if necessary, to melt some more. Stir to see where you are on getting the ingredients to make a smooth, silky mixture.
When completely melted together and smooth, add 1 teaspoon vanilla and combine well. Set aside to cool.
When the fudge is cool, using a hand mixer, beat it with a another stick of butter. This will whip it up to a peanut butter filling.
Note: You won't use all of this to fill the cupcakes. You'll end up with at least half of it left over to finish with the cocoa and cream for frosting.
With a small spoon or melon baller, scoop out a little hole in the top of each cupcake.
Fill a pastry bag with about 1/4 cup of the peanut butter filling. Fill each hole with peanut butter filling.
Add 1/2 cup of unsweetened cocoa to the leftover peanut butter filling. Whip it with your mixer into frosting, adding just enough of the 1/4 cup of cream to get it the right consistency. You may not need all of it.
When the frosting has whipped up light and fluffy, add to a clean pastry bag and pipe onto the tops of the cupcakes. Alternatively, you could just spread it over the cupcakes with a knife if you aren't trying to be fancy.
When making the peanut butter fudge, it turned out dry and crumbly for me. I emailed back and forth with Libby about it and we determined it could be the lack of humidity where I live vs. high humidity where she lives. I remade it with the following changes:
Melt the peanut butter, butter, and salt together then beat in 1 cup of confectioners' sugar until smooth. Add an additional cup of confectioners' sugar and beat until smooth. If mixture is very soft, continue adding in confectioners' sugar, 1/4 cup at a time until mixture is stiff, but still smooth. Stir in 1 teaspoon vanilla then proceed with recipe as written above.
I made the peanut butter fudge an additional time following my instructions above. Instead of turning it into filling and frosting, I patted it into a rectangle and refrigerated until firm. I then melted a 1/4 cup chocolate chips and spread over the top. Once the chocolate set, I cut into squares. The candy (as well as the cupcakes) received rave reviews!
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