Possible filling or icing

So I found this icing recipe after you had mentioned wanting the peanut butter filling.

Ingredients:

• 1/3 cup solid vegetable shortening
• 1/3 cup butter
• 3/4 cup peanut butter
• 1 teaspoon of pure vanilla extract
  
• 4 cups (approx. 1 lb.) confectioners' sugar, sifted
• 4-6 tablespoons milk

Instructions:

Step 1

Cream shortening and butter with electric mixer. Add peanut butter and vanilla. Gradually add sugar, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar has been mixed in, icing will appear dry. Add milk, one tablespoon at a time, and beat at medium speed until light and fluffy.

Step 2

Keep icing covered with a damp cloth until ready to use. For best results, keep icing bowl in refrigerator when not in use. Refrigerated in an airtight container, this icing can be stored 2 weeks. Re-whip before using.

I don't think it'd be very hard to convert to filling... Minor adjustments. I want to try it but the perfecting of the original filling has to be a first. The filling I'm currently working on is a simple vanilla cream that my father sent me. I shall keep you posted with tomorrows results of the vanilla filling.